U.S. Air Force Senior Airman Steven Schwab, 380th Expeditionary Maintenance Squadron aircraft structural repair technician, cleans up the edge of a titanium metal piece at Al Dhafra Air Base, United Arab Emirates, Dec. 9, 2018. (U.S. Air Force photo by Senior Airman Mya M. Crosby)

The Potential Use of Hydrogen Recovery for the Production of Titanium

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Two of us (BOD/TAC) have previously described field-proven metal extraction mining technique (https://www.hstoday.us/subject-matter-areas/emerging-innovation/perspective-take-a-cue-from-kazakhs-and-leap-forward-in-security-minded-metals-extraction/). The concept of reducing the cost of production of titanium sponge by replacing expensive and environmentally hazardous thermal conversion by magnesium to the reduction of titanium tetrachloride with hydrogen is proposed.

According to world mining experts, the main driver of titanium consumption will continue to be, as previously, the global aerospace industry. Thus, according to VSMPO forecast, the demand for titanium in the global aerospace industry will grow annually by 5-7 percent, or exceed 85,000 tons in 2018 [1].

Promising industrial uses of titanium appear to be concentrated mainly in chemical and petrochemical plants, as well as heat exchangers, as this sector has shown very high growth rates in recent years, especially due to the rapid increase in the construction of worldwide chemical plants and power plants. In order to provide these industries with titanium and expand titanium applications, it is necessary to reduce its cost of production. Therefore, titanium manufacturers are actively looking for new production technologies that will significantly reduce the cost of titanium.

The Kroll process is currently the most commonly used commercial titanium sponge manufacturing technology, as well as the standard of comparison with new technologies. Although the world is currently continuing research aimed at creating new technologies for continuous production to allow the recovery of titanium metal at a lower cost, there was only one enterprise (capacity of 2,000 tons per year) which did not use the Kroll process in 2013 [2].

The Kroll method used now can be divided into the following main stages:

А) Processes of a titanium branch:

  • Melting ilmenite to obtain titanium slag

FeO • TiO2 + С = Fe + TiO2 + CO,    1650 °С                                               (1)

2)    Chlorination of slag (titanium dioxide)

TiO2 + 2Cl2 + 2С = TiCl4 + 2СО    700-900 °С                                           (2)

3)    Purification of TiCl4 from dust and gases – СО, СО2 and various chlorides 4)    Titanium sponge: thermal production with a magnesium

TiCl4 + 2Mg = Ti + 2MgCl2   800-900 °С; 30-50 hours                  (3)

B) Processes of the magnesium branch:

5)     Dehydration of carnallite MgCl2 • KCl • 6H2O. in tubular rotary furnaces and in chlorination furnaces 550-600 ° C; 6)    Electrolysis of a chloride melt to produce magnesium and chlorine:

МgСl2 → Мg + Cl2     670-720 °С                                                    (4)

In general, magnesium-chloride technology for titanium sponge seems “closed” (only titanium exists from scheme) and therefore was industrially acceptable:

However, the implementation of this method revealed many shortcomings. The main issue is the generation of large amounts of solid, liquid and gaseous chlorine-contaminated wastes.

The major components of the main processing in the cost of titanium sponge processing [3], in percentages, are:

– cost of raw materials:10 percent

– processing and re-melting of rutile into titanium slag:10 percent

– chlorination of titanium raw materials into TiCl4: 20 percent

– cost of magnesium production: 35 percent

The high proportion of magnesium in the cost of titanium is striking. Therefore, the improvement or replacement of this process is the most promising for reducing the cost of titanium production.

Hydrogen can be considered as an alternative reducing agent for titanium tetrachloride. It should be noted that hydrogen reduction has been proposed for both titanium dioxide and titanium tetrachloride. Conceptually, this method is attractive, since the only solid produced by reactions at these temperatures is titanium, so the design of a continuous reactor with such a reducing agent is theoretically possible. [4].

Based on the analysis of scientific and technical data, we propose the following improvements for titanium plants:

  1. Reject magnesium used processes (5 and 6 above)
  2. Process 4 reduction with magnesium to replace into reduction with hydrogen
  3. Chlorine for reaction 2 and Hydrogen for reaction 4 are delivered from plants of caustic soda, for which they are often by-products requiring disposal

The expected effect of such a scheme is a reduction in the cost of the sponge by 35 percent or more, and an improvement in environmental friendliness. The economic comparison of the reagents of the hydrogen and magnesium thermal methods is quite clear in favor of the hydrogen scheme:

TiCl4 + 2 Mg = Ti + 2MgCl2, (5) Consumption is 1 kg of magnesium per 1 kg of titanium, or $3-4 in the price range of $7- 10 for 1 kg of titanium

TiCl4 + 2H2 = Ti + 4HCl, (6) Consumption is 0.083 kg of hydrogen per 1 kg of titanium, or $0.17 of the price of between $7-10 for 1 kg of titanium

The expected effect is savings of at least $4 per 1 kg of titanium.

It is clear that thermodynamically, reaction (6) is complicated. However, there are ways to implement it in stages.

The sequence of reactions of stepwise reduction of tetrachloride to titanium by hydrogen is as follows:

In addition to thermodynamic issues, another difficulty for technologists may be kinetics, that is, the low speed of some of the proposed reactions.  One of the solutions in these cases can be the use of a new generation of modern devices called “micro reactors,” allowing one to dramatically intensify both homogeneous and heterogeneous processes [5]. In addition, having closed cycles for intermediate products, it is then possible to use primarily the “fast” part of the kinetics of processes, without spending the time and energy on fine-tuning the degrees of completion of reactions to unnecessarily high values. This would allow industry to provide an acceptable compromise between the rates and degrees of completeness of reactions.

In summary, the Kroll process, which is now mainly used to produce titanium, is a high-cost method that drives the high cost of titanium sponge. Processing it into ingots also requires a lot of energy and specialized equipment. Preliminary studies by the authors have shown the potential of titanium recovery by hydrogen, with a significant reduction in cost, as well as increased environmental friendliness of the process.

References:

1) Kazakhstan Today – world market of titanium for the last two months prices have stabilized (https://www.kt.kz/rus/economy/na_mirovom_rinke_titana_za_poslednie_dva_mesjaca_ceni_stabilizirovalisj_obzor__1153582958.html).

2) World titanium market trends and prospects: http://www.ereport.ru/articles/commod/titanium.htm

3) Hartmann A. D., Gerdemann S. J., Hansen J. S., “Producing Lower-Cost Titanium for Automotive Applications”, JOM. – Sept. 1998. – R. 16-19.

4) “Titanium: Past, Present and Future”, NMAB-392 (Washington, DC.: NRC, 1983).

5) Borovinskaya E. S., Reshetilovskiy V.P., “Prospects of intensification of heterogeneous processes in micro reactors”, Journal of D. I. Mendeleev’s Chemical Society, 2011. T.  LV, No. 2 .p. 78 – 84.

Dr. Kalilallo BAYTASOV writes about economic efficiency of metals extraction technologies and digitalization of these processes. He has been working in industrial and scientific organizations for more than 20 years. He was a member of a project team managing JSC Kazatomprom’s research programs from 2008 to 2015. Dr. BAYTASOV is the author or co-author of more than 20 scientific articles and holds several patents. He graduated from the Institute of Technologies of Omsk (OTI) in 1999, defended his PhD thesis in Economics in 2005 at St. Petersburg University of Economics and Finance, and completed his Master’s thesis in International Relations at the National Research Nuclear University “MEPhI” in Moscow. At present Dr. BAYTASOV is working as an Assistant Professor of the School of Engineering Management at Almaty University of Management and is Head of the Cybersecurity Laboratory at Kazakh-British Technical University (in Almaty, Kazakhstan).

Dr. A. Mukusheva writes about the technology of extraction of valuable components from various ores and industrial waste. She has experience in the scientific departments of large industrial enterprises in Kazakhstan, such as: Zhezkazgantsvetmet, Zhezkazganredmet, and Kazatomprom. She is the author of more than 10 patents and more than 100 scientific papers.   Dr. Mukusheva also has experience in the conservation and management of nuclear technological knowledge-with the creation of a Knowledge Base and publications in this area.   She graduated from Karaganda State University in Kazakhstan and she is certified as an Associate Professor in Kazakhstan.

Dr. Thomas “Tommy” Cellucci writes about the intersection of emerging technology, commercialization, and implementation to protect the homeland. Dr. Cellucci has been a senior executive in both the private and public sectors for over 39 years. He served as the US Government’s first-ever Chief Commercialization Officer after turning around his fourth high technology firm, working for both President George W. Bush and President Obama. Thomas is a turn-around artist on Wall Street and serves on many global Boards. He also currently assists President Trump’s team when asked. Thomas has authored or co-authored 25 scholarly books and over 231 high-tech business articles. Cellucci earned a PhD in Physical Chemistry from the University of Pennsylvania (1984), an MBA from Rutgers University (1991) and a BS in Chemistry with Honors from Fordham University (1980). He serves on 23 Boards and is the recipient of many awards. He holds two endowed Chairs at prestigious universities in Kazakhstan, as well as taught at Harvard Business School, Princeton University and the University of Pennsylvania. He and his wife Julie spent their free time with their children and grandchildren.

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Dr. Baurzhan Duisebayev writes about different technologies for effective extraction of metals from poor ores and/or waste materials. He has been a well-respected leader in both the private and public sectors for over 30 years. He coordinated all the research programs of Kazatomprom from 2001-14. Dr. Duisebayev has authored or co-authored 40 technological patents, and about 80 scientific articles. He graduated from Tomsk Polytechnical University (TPU) in 1982 and defended his candidate of science dissertation in 1985 in TPU and his Doctoral dissertation in 1997 in Irkutsk Polytechnical University. Dr. Duisebayev serves also as a Professor-lecturer for magistrates-geologists in the Kazakh National Scientific Research Technical University. He and his wife Rauza spent their free time with their children and grandchildren.

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