Mechanism of Nickel, Magnesium, and Iron Recovery from Olivine Bearing Ore during Leaching with Hydrochloric Acid Including a Carbonation Pre-Treatment

Round 1

Reviewer 1 Report

Dear author!
I have read your article "Mechanism of metal recovery from olivine bearing ore during leaching with hydrochloric acid including a carbonation pre-treatment". This article may be interesting, but it needs improvement now.

I have some comments and questions:
1) This article contains a long Introduction, which describes various works on the subject. It is necessary to systematize the work of other authors and come to a certain conclusion, not to paint each work.
2. The concentration of hydrochloric acid during leaching is an important factor affecting the metal leaching process. It is necessary to obtain and analyze such dependencies.
3. Why do you present experimental data where the particle size is 100-150 µm in section 3.2? Then, in the Discussion section, you compare the results for 20 µm.
4. In the Results section, it is not recommended to refer to the work of other researchers by paraphrasing their results. It is necessary to rewrite this section by describing your results in a more complete and detailed way, emphasizing the importance of the work.
5. Probably, the letter "r" is missing in line 57 of the word Fosterite.
6. In section 2, "Name, model, city, state, country", you should add to describe the equipment used in the work.

Author Response

Dear Reviewer,

Thank you very much for your invested time and valuable comments. We have carefully read your comments and prepared our answers in red Color in our cover letter.

1) This article contains a long Introduction, which describes various works on the subject. It is necessary to systematize the work of other authors and come to a certain conclusion, not to paint each work.

We removed 5 first publications and discussion about nickel lateritic ores. We started directly with olivine and his treatment. One conclusion about previous work is present in this text:

Generally, the previously mentioned results studied carbonation [3-13], but not the prevention of silica gel formation and mechanism of metal extraction form the obtained solution is missing. A flowchart of new combined process of carbonation of olivine and a subsequent leaching can be a new strategy for metal recovery.

2. The concentration of hydrochloric acid during leaching is an important factor affecting the metal leaching process. It is necessary to obtain and analyze such dependencies.

You have right. We will add 3 new diagrams (as shown in cover letetr). An increase of concentration from 1 to 2 M increases the leaching efficiencies of nickel, iron and magnesium

Figure 11. Leaching efficiency of nickel from a carbonated olivine depending on concentration of hydrochloric acid and temperature for the fraction 20 – 63 µm

Figure 12. Leaching efficiency of magnesium from a carbonated olivine depending on concentration of hydrochloric acid and temperature for the fraction 20 – 63 µm

 

3. Why do you present experimental data where the particle size is 100-150 µm in section 3.2? Then, in the Discussion section, you compare the results for 20 µm.

 

We tested the both fraction, but the carbonation of Fraction of 20-63 µm has shown the best results. We have written it:

“Dissolution of the olivine bearing ore ( <20 µm, 20-63 µm, 100-150 µm) was studied with hydrochloric acid between 50 °C and 90 °C in duration of 30 min to 180 min in order to establish the leaching efficiency of nickel, magnesium and iron. A positive influence of the decreased particle size (from 100-150 µm to fraction below 20 µm), increased reaction time, and temperature on the leaching efficiency was found in all cases.” We used this fraction in scale up conditions.

4. In the Results section, it is not recommended to refer to the work of other researchers by paraphrasing their results. It is necessary to rewrite this section by describing your results in a more complete and detailed way, emphasizing the importance of the work.

We have rewritten this part. We put the influence of temperature in order to explain better our results. We removed text regarding the other authors and written the importance of the work. We improved our conclusion and put a flowchart regarding our developed combined process.

5. Probably, the letter "r" is missing in line 57 of the word Fosterite.

Thank you we change it. (forsterite)

6. In section 2, "Name, model, city, state, country", you should add to describe the equipment used in the work.

Type ( Company, City, state Country)

Type PW2404 (Malvern PANalytical, Malvern, United Kingdom).

Milling was performed using Roller Mill, Type LWBP 2/2 (Karl Merz Maschinenfabrik GmbH, 1972 (year of manufacture), Heschingen, Germany),.

Sieving was performed using Sieving Maschine, Type Prüf 86 (Siebtechnik GmbH, Mühlheim an der Ruhr, Germany).

Semi-automated mineralogical analyses were performed by applying a Quanta 650-F QEMSCAN© (FEI/Thermo Fischer, Hilsboro, Oregon, USA) scanning electron microscope (SEM) at the Institute of Applied Mineralogy and Economic Geology, RWTH-Aachen University.

Author Response File: Author Response.pdf

Reviewer 2 Report

A wide revision of the manuscript was necessary before their possible publication

Abstract, Introduction, Results, Discussion and Conclusions sections needs to be improved. Also, the quality of the Figures 

seeing the attachment

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thank you very much for your invested time and valuable comments. We have carefully read your comments and prepared our answers in red Color in my cover letter. Your Questions are here represented in bold letters.

Abstract need to be re-written. It start with the sentence “This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave”. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching. Therefore, abstract may reflect that and to start with the problem of scaling in the traditional processing of nickel ore laterites.

We improved it using your proposal

This work follows from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching.

 

Introduction

Lines 51-54. “Kremer et al. [3] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

 

What kind of “mineral input materials”? This paragraphs needs to be improved.

 

Kremer et al. [3] investigated the possible mineral input materials such as forsterite and Basalt.

Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

These experiments are important for the choice of materials for the carbonation regarding to the relationship between MgO and SiO2. The scale formation is dependent on the content of SiO2, its structure and form. Because of formation of nanosized silica passive layers these Experiments decrease scale Formation during leaching.

 

Lines 67-71. “Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr⁶⁺ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

The previous mentioned experiments by Turri et al. [12] have performed in a rotary autoclave ensuring an information about chemical composition of obtained solution and a way to remove chromium from final solution during carbonation of olivine. These results were used as an initial point for the planning of experiments in work of Stopic et al. [9, 10], but an information about metal recovery from solution was missing.

Generally, the previously mentioned results studied carbonation [3-13], but not the prevention of silica gel formation and mechanism of metal extraction form the obtained solution is missing. A flowchart of new combined process of carbonation of olivine and a subsequent leaching can be a new strategy for metal recovery.

Materials and methods

Where the sample has been selected?

According to our experiences and literature review the sample was selected after milling and sieving.

 

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed.

The statistical Analysis is not performed, but chemical analysis was performed using different Methods (ICP, XRF) in two laboratories in Germany.

Quality of Figure 2 and Figure 3 could be improved or can be eliminated or substitute by a detailed diagram of the equipment.

We improved it. We put new picture of leaching reactor (Figure 2) and our autoclave (Figure 3).

Figure 2: Leaching Reactor

Figure 3: Carbonation process of olivine and a filtration with a sampling

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

The sampling during leaching was performed each 60 min.

A more detailed description of the experimental section was necessary. How was performed the milling process?

Milling was performed using Roller Mill, Type LWBP 2/2 (Karl Merz Maschinenfabrik GmbH, 1972 (year of manufacture), Heschingen, Germany). Sieving was performed using Sieving Maschine, Type Prüf 86 (Siebtechnik GmbH, Mühlheim an der Ruhr, Germany)

How many sample was used in each leaching experiment?

We used three different fractions of olivine: <20 µm, 20-63 µm and between 100 and 150 µm, as shown in Table

Figure 5 needs to be improved. Probably this figure could be included in the Results and Discussion as part of the discussion.

You have right. This figure is now included in the Results and Discussion as part of the discussion.

3. Results and discussion

The paragraph “To evaluate the overall capability of the carbonation process, an experiment was performed using Norwegian olivine (20 – 63 μm) at 175 °C, CO2-pressure of 71.5 bar, 120 min, 600 rpm, in a 9.9 L autoclave (as shown in Figure 3) in the presence of additives of sodium carbonate, oxalic and ascorbic acid” was in the experimental section.

Figure 8. Please, indicated in the Figure the SiO2 or MgO particles

We did it.

Authors said “a carbonation pre-treatment in an autoclave leads to an increased leaching efficiency from 25 – 30% to 40 – 45% at 50 °C for all recovered metals”. Please, discuss each one.

After Figure 14: Comparison of the leaching efficiency of olivine without carbonation and with olivine with carbonation as a pre-treatment step, 20 – 63 µm, 50 °C, 120 min, 1M HCl, 300 rpm, I put next comments:

An increase of the leaching efficiency for nickel from 25 to 40 % at 50°C was reached in the presence of carbonation pre-treatment. Similar effects were obtained for magnesium and iron under same conditions

Figure 11 shows leaching efficiency depending on temperature. What temperature?

This is leaching temperature.

Leaching efficiency depending on a leaching temperature, 100 – 150 µm, 90min, 1M HCl, 300 rpm

Figure 12. Quality is not good. Please, made a picture of silica gel.

We removed picture of silica gel. We can not offer better resolution of silica gel.

If leaching was performed at different temperatures, why authors only show results obtained at 50ºC? 

We added three new diagrams with results at 50°C, 80°C and 90°C (figs. 11, 12 and 13). At 50 °C we did not have problems with an evaporation of hydrochloric acid. For a possible scale experiments this temperature will be an ideal choice regarding to a cost effective and environmentally- friendly process.

 

Conclusions:

Conclusions need to be clear and only that conclusions obtained from experimental results. All this section need to be re-written.

For example, the sentences

“In order to understand the exact processes within the carbonation process more detailed analysis are proposed with regards to possible dissolution of olivine and the associated and bonded nickel by carbonation”

Or

“The selectivity of leaching and separation process can be studied using other hydrometallurgical operations such as solvent extraction and ion exchange for selective leaching of nickel, magnesium and iron”

Are not a conclusion.

Thank you very much for your proposal. We have fully rewritten it.

We have removed these two sentences and a conclusion was re-written

“SEM analysis of the carbonated product at 175°C and 71.5 bar has shown that magnesite crystals (2 – 5 µm) and very small particles of amorphous SiO₂ (100 – 200 nm) are formed as rhombohedrons or hexagonal prisms at the surface of partially carbonated magnesium silicate. A comparison of the leaching efficiencies at 50°C of the investigated metals before carbonation and with carbonation confirms an increased leaching effiency of nickel from 25 to 40%, what is also observed for magnesium and iron. An increase of temperature between 50 and 90°C, a decrease of particle size from 150 µm to 20 µm and an increase of reaction time from 60 and 240 min leads to an increased leaching efficiency of nickel, magnesium and iron. A new mechanism of combained carbonation pre-treatment and a leaching was proposed. Our new developed process was presented at Figure 16.

Figure 16. Metal recovery from olivine bearing ore during leaching with hydrochloric acid including a carbonation pre-treatment

In order to spare an added water (s/L: 0.1) enabling an enrichment of metals during new carbonation, obtained waste solution after filtration was again used in an autoclave, what is environmental friendly.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Title: « Mechanism of metal recovery from olivine bearing ore during leaching with hydrochloric acid including a carbonation pre-treatment.”. What metals are recovered? I suggest to rephrase in a clear way for readers to understand. I would suggest the following title: “Extraction of nickel, iron and magnesium from olivine bearing ore by leaching with hydrochloric acid”.

 

Abstract: I suggest to add a short context in the beginning of this section. If no context readers are not going to consider this paper.

Abstract: “…This work follows on from previous studies which showed that mineral sequestration…”. It is not understandable. The authors likely wanted to say: “…This work follows previous studies showing that mineral sequestration…”.

Abstract: “… Amorphous silica and magnesite or calcite, respectively, were the main reaction products…”. Reaction products from what reaction?

Abstract: I highly recommend to rephrase and reorganize this section. As it is, it is not understandable.

Keywords: Silica gel; pre-treatment; autoclave; mechanism, are not suitable keywords as they are not appearing in the title.

 

Introduction: What is the context of this study?

 

Line 135-136: “…Generally, the previously mentioned results studied carbonation [3-13], but not the prevention of silica gel formation and mechanism of metal extraction form the obtained solution is missing…”. Please rephrase as it is not understandable.

 

Legends to figures and tables: Please complete the legend information when necessary. The legends must contain all the information required to understand the content of the figure or table, without in any case referring to the main text of the manuscript. Do this even if multiple lines will be required.

 

Line 386: “…subsequent leaching in hydrochloric acid, as shown in Error! Reference source not found…. ». ???

Line 393-394: « … The investigated leaching mechanism with carbonation as pre-treatment process, visualised in Error! Reference source not found.,… ». ??

Conclusion: Add a short context here. Most of the readers read the Abstract and the Conclusion. Thus full information of the study has to be written in both sections.

 

Line 406-407: « … The results of the carbonation pre-treatment prior to leaching show that it is a promising and technically feasible step to increase the efficiency…”. Increase the difference of what?

 

Line 418: “…fullx developed process… ». Fullx ?

Author Response

Dear Reviewer,

thank you very much for your invested time and valuables comments. We have carefully read your remarks. Now we are sending our answers!

1. Title: « Mechanism of metal recovery from olivine bearing ore during leaching with hydrochloric acid including a carbonation pre-treatment.”. What metals are recovered? I suggest to rephrase in a clear way for readers to understand. I would suggest the following title: “Extraction of nickel, iron and magnesium from olivine bearing ore by leaching with hydrochloric acid”.

We changed it. Mechanism of nickel, magnesium and iron recovery from olivine bearing ore during leaching with hydrochloric acid including a carbonation pre-treatment

 

2. Abstract: I suggest to add a short context in the beginning of this section. If no context readers are not going to consider this paper.

Abstract: “…This work follows on from previous studies which showed that mineral sequestration…”. It is not understandable. The authors likely wanted to say: “…This work follows previous studies showing that mineral sequestration…”.

This work follows on from previous studies showing that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave.

 

3. Abstract: “… Amorphous silica and magnesite or calcite, respectively, were the main reaction products…”. Reaction products from what reaction?

Abstract: I highly recommend to rephrase and reorganize this section. As it is, it is not understandable.

Amorphous silica and magnesite, respectively, were the main reaction products in a carbonation of olivine under high pressure conditions.

 

4. Keywords: Silica gel; pre-treatment; autoclave; mechanism, are not suitable keywords as they are not appearing in the title.

We changed it.

Keywords: olivine; carbonation; recovery, nickel, magnesium, iron, leaching

 

5. Introduction: What is the context of this study?

This study explains additionally a behavior of metals such as nickel, magnesium and iron during a carbonation of olivine bearing ore and leaching of a carbonated solid product.

 

6. Line 135-136: “…Generally, the previously mentioned results studied carbonation [3-13], but not the prevention of silica gel formation and mechanism of metal extraction form the obtained solution is missing…”. Please rephrase as it is not understandable.

Generally, the previously mentioned results studied carbonation of olivine [3-13], but an information about an extraction of nickel, magnesium and iron from the obtained solution is missing.

 

7. Legends to figures and tables: Please complete the legend information when necessary. The legends must contain all the information required to understand the content of the figure or table, without in any case referring to the main text of the manuscript. Do this even if multiple lines will be required.

We have completed it.

 

8. Line 386: “…subsequent leaching in hydrochloric acid, as shown in Error! Reference source not found…. ». ???

We changed it.

 

9. Line 393-394: « … The investigated leaching mechanism with carbonation as pre-treatment process, visualised in Error! Reference source not found.,… ». ??

We changed it.

10. Conclusion: Add a short context here. Most of the readers read the Abstract and the Conclusion. Thus full information of the study has to be written in both sections.

We added this sentence in Introduction „Generally, the previously mentioned results studied carbonation of olivine [3-13], but an information about an extraction of nickel, magnesium and iron from the obtained solution is missing.“

We added this sentence in a conclusion: “A new mechanism of metal recovery during combined carbonation pre-treatment and a leaching offers an additional information about a behavior of nickel, magnesium and iron.

 

11. Line 406-407: « … The results of the carbonation pre-treatment prior to leaching show that it is a promising and technically feasible step to increase the efficiency…”. Increase the difference of what?

The results of the carbonation pre-treatment prior to leaching show that it is a promising and technically feasible step to increase a dissolution efficiency of nickel, magnesium and iron from olivine bearing ore.

 

12. Line 418: “…fullx developed process… ». Fullx ?

It was mistake. “fully developed process”.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors!
I recommend that you check the text more thoroughly for errors and defects.
There are some comments that need to be corrected:
1. line 37 - start a paragraph with an indent
2. lines 159-160 - you repeat that sentence below!
3. line 170 - start a paragraph with an indent.
4. Figures 11-13 should be made as big as the others.
5. line 385 - Figure 5?! Not in order.
6. lines 386, 394 - There's an incomprehensible phrase "Error! Reference source not found..."
7. Conclusion: I do not recommend to give a picture and refer to them in this section. It can be placed in the Discussion.

Author Response

Dear Reviewer,

thank you very much for your invested time and valuables comments.

We improved our text with your remarks!

1. line 37 - start a paragraph with an indent

We changed it!

2. lines 159-160 - you repeat that sentence below!

We removed this repeated sentence!

3. line 170 - start a paragraph with an indent.

We did it.

4. Figures 11-13 should be made as big as the others.

We increased the Figures 11-13.

5. line 385 - Figure 5?! Not in order.

We have right. We put the Figure 15.

6. lines 386, 394 - There's an incomprehensible phrase "Error! Reference source not found..."

We changed it!

7. Conclusion: I do not recommend to give a picture and refer to them in this section. It can be placed in the Discussion.

We put the Figure 16 at the End of our Discussion!

 

Author Response File: Author Response.pdf

Reviewer 2 Report

 

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract

“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

Materials and methods

Where the sample has been selected? Please, indicate it

Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed

Abstract
“This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”
In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.
Introduction
Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.
What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?
“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.
This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.
It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.
Materials and methods
Where the sample has been selected? Please, indicate it
Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it
Quality of Figure 2 and Figure 3 has been improved
The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?
A more detailed description of the experimental section was performed

v

Author Response

Dear Reviewer,

Thank you very much for your invested time and valuable comments. We have carefully read your remarks. Now we are sending our answers!

This work follows on from previous studies which showed that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching”

In which process? The abstract should introduce the reader in the subject. Only in the middle of the abstract authors said that metals extracted would be nickel, iron and magnesium from olivine bearing ore using hydrochloric acid. Please, authors need to improve the abstract.

 

This is leaching process. We changed title of paper and re-written our abstract:

 

Abstract: This work follows on from previous studies showing that mineral sequestration by carbonation of magnesium or calcium silicates under high pressure and high temperature can be successfully carried out by processing in an autoclave. The paper is focused on the influence of experimental parameters on avoiding scale formation during pre-treatment in an autoclave and a subsequent leaching. Amorphous silica and magnesite, respectively, were the main reaction products in a carbonation of olivine under high pressure conditions in an autoclave. In addition, the examined peridotites may be accompanied by small to medium amounts of nickel or further metals, the recovery of which will be investigated in the present study: Extraction of metals such as nickel, iron and magnesium from olivine bearing ore using hydrochloric acid under atmospheric pressure was studied between 50 and 90 °C in 1 hour. The obtained results have shown maximal leaching efficiency of about 35% for Ni, Fe and Mg under atmospheric pressure, in comparison to more than 60% obtained under same conditions after a carbonation pre-treatment in an autoclave. Silica gel was formed during leaching without a pre-treatment of peridotite blocking the leaching process, which is not the case for the pre-treated material. The influence of temperature, reaction time, particle size and pre-treatment of peridotite in an autoclave during carbonation at 175 °C and 71.5 bar was studied. A new mechanism model for metal extraction from olivine-bearing ore by avoiding silica gel formation during leaching with hydrochloric acid including a carbonation pre-treatment is proposed. This study explains additionally a behavior of metals such as nickel, magnesium and iron during a carbonation of olivine bearing ore and leaching of a carbonated solid product.

Introduction

Authors need to make corrections suggested in the initial revision “Kremer et al. [6] investigated the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials for the carbonation that are covered by this study represents more than 50% of the global olivine production. Reaction products are amorphous silica and magnesite or calcite, respectively”.

What kind of “mineral input materials”? OK. It has been corrected in the text. However, other suggestions have not been corrected. This paragraphs needs to be improved. Authors should make a better relationship between this paragraph and the previous one. Why these experiments decrease scale formation?

 

“The carbonation experiments were performed in water solution under high pressure conditions. During carbonation a silica passive layer was formed by nanosilica particles, which decrease a scale formation”

“Turri et al. [9] performed a flotation of chromite as pre-treatment of olivine before carbonation for CO2 sequestration in order to increase carbonation efficiency and decrease the toxicity of the solution because of the presence of Cr6+ -ions. The mixed crystal is mainly used in the metallurgical field for different applications. Because of its refractory properties, Mg-based compounds serve the furnace construction”.

This paragraph is interesting. However, it should better related with the rest of the Introduction. The Introduction must link the different studies to reach the final objective of the article. In general, Introduction could be improved with a better relationship between paragraphs.

We added new sentences in order to connect it with a next paragraph. „High interest was developed for an using of the produced nanosilica particles. Main problem was how to separate a produced silica from a magnesite.“

It should be noted that at the end of the Introduction of the revision version, the authors include a paragraph that improves it considerably. However, in general, the relationship between the different paragraphs of the introduction should be improved.

We added "Generally, the previously mentioned results studied carbonation of olivine [3-13], but an information about an extraction of nickel, magnesium and iron from the obtained solution is missing. A flowchart of new combined process of carbonation of olivine and a subsequent leaching can be a new strategy for metal recovery."

 Materials and methods

Where the sample has been selected? Please, indicate it 3, Table 1. Authors said “Regarding the different particle size fractions it is visible that there are no significant deviations in the composition especially for the investigated oxides of nickel, magnesium and iron”. However, statistical analysis was not performed. Please, correct it

All 3 samples were used in our work. We have shown of chemical analysis of samples.

Quality of Figure 2 and Figure 3 has been improved

The leaching process took a total of up to minutes, with samples being taken periodically. How often is the sample taken?

A more detailed description of the experimental section was performed.

The leaching process took a total of up to 240 minutes, with samples being taken periodically. The sampling during leaching was performed each 60 min.

We improved also our Discussion and Conclusion

 

Author Response File: Author Response.pdf

Reviewer 3 Report

NA

Author Response

Dear reviewer,

thank you very much for your invested time.

We checked our English in text.

 

Best regards

Srecko Stopic

Round 3

Reviewer 2 Report

    The authors have improved the manuscript and have made most of the corrections but there are still some to do.

In two previous revisions I said that authors need to correct some questions that continuos without change. For example. In the discusion of Table 1 authors said that there are not significant deviations. If stadistical analysis was not performed, it was not possible to said that.

Quality of some figures are not improved. For example, quality of Figure 16 needs to be improved

.  

Author Response

Dear Reviewer,

thank you very much for your invested time and valuable comments. I have always tried to give all answers on your questions. My apology, if we did not fill your expectations

Your questions and our answers:

"The authors have improved the manuscript and have made most of the corrections but there are still some to do.

In two previous revisions I said that authors need to correct some questions that continuos without change. For example.

1. In the discusion of Table 1 authors said that there are not significant deviations. If stadistical analysis was not performed, it was not possible to said that. We Changed our Statement in text " Athough a statistical analysis was not performed, a chemical analysis of different particle size fractions shown in Table 1, has revealed minimal deviations in the composition of the investigated nickel oxide, magnesium oxide and iron (III) oxide in our initial sample. 

2. Quality of some figures are not improved. For example, quality of Figure 16 needs to be improved.

We have improved Figure 16, and put it in our cover letter  and in a final version.

I hope that you are sufficiant with these answers.

 

Best regards

Srecko Stopic

Author Response File: Author Response.pdf