Processing of Ukrainian Ilmenite-bearing Heavy Sands as a Contribution to Improving Europe’s Self-supply in Critical Raw Materials from Its Own Deposits
Presentation of a PhD-Project
Authors:
Dipl.-Ing. Michael Lechner, Eva Gerold, Helmut Flachberger
The article delves into the critical importance of securing a stable supply of critical raw materials (CRMs) for Europe's industrial competitiveness and green transition, with a particular focus on titanium. It examines the current dependence on imports and the vulnerabilities this creates, emphasizing the need for innovative extraction and processing methods to comply with the European Commission's Critical Raw Materials Act. The REPTiS project, a Horizon Europe initiative, is presented as a pioneering effort to establish a sustainable and resilient supply chain for titanium and other selected CRMs within the EU. The article provides a comprehensive overview of the titanium production process, from the sustainable extraction of ilmenite from heavy sands to the patented, low-energy Velta Ti process, and further downstream processing techniques. It also explores the current value chain of titanium production, highlighting its energy-intensive nature and high ecological carbon footprint. The article discusses the potential for optimizing the beneficiation of heavy sands, including the recovery of rare earth elements, niobium, tantalum, and scandium, and the valorization of by-products. It concludes with an outline of the project's aims and work approach, emphasizing the importance of reliable data collection and assessment for future mining activities and related projects.
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Abstract
The REPTiS project (Responsible Extraction and Processing of Titanium and Other Primary Raw Materials for Sourcing EU Industrial Value Chains and Strategic Sectors) addresses the urgent need for a secure and sustainable supply of titanium and other critical raw materials (CRMs) within the EU. Given the EU’s dependency on imports and the risks of supply chain disruptions, REPTiS focuses on the responsible extraction and processing of titanium and other CRMs from heavy mineral sands. The main aim of this dissertation is to optimize the current beneficiation process in Ukraine to enhance ilmenite (FeTiO3) recovery while developing new approaches for extracting valuable by-products such as rare earth elements, niobium, tantalum, and scandium. Further, a whole new processing scheme for unused weathering crust sands will be developed and implemented in the beneficiation process. Additionally, the potential use of kaolinite as an additive feedstock in the concrete industry will be evaluated.
Notes
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1 Introduction
The EU’s industrial competitiveness and green transition rely heavily on a steady supply of critical raw materials (CRMs). Titanium, which has been on the CRM list since 2017, is indispensable in producing high-strength lightweight alloys and corrosion-resistant materials, integral to key sectors such as aerospace, defense, medical equipment, and renewable energy technologies. Despite the significance of critical raw materials, the EU is heavily dependent on imports, leaving it vulnerable to supply disruptions caused by geopolitical instability, trade restrictions, and market monopolies. To comply with the Critical Raw Materials Act of the European Commission, it is essential to research the possibilities of mining, processing, and innovative extraction methods on deposits containing critical raw materials. Due to the high proportion (up to approx. 30%) of several critical raw materials (Ti, Hf, Ta, Nb, Rare Earth Elements like Ce, La, Nd, etc.) in heavy sands, investigations within the EU are mandatory.
REPTiS stands for Responsible Extraction and Processing of Titanium and Other Primary Raw Materials for Sourcing EU Industrial Value Chains and Strategic Sectors [1, 2]. It is a Horizon Europe Project motivated by the urgent need to establish a secure, sustainable, and resilient supply chain for titanium and other selected CRMs within the EU. The global objective is to offer a sustainable and energy-efficient solution for responsible extraction and processing of Titanium and other Primary Raw Materials to supply EU industrial value chains and strategic sectors.
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As shown in Fig. 1, the REPTiS consortium comprises 11 partners from seven EU/EEA countries (Belgium, France, Germany, Poland, Spain, Sweden, and Austria) and two partners from the strategic partner country Ukraine, covering the entire value chain of Titanium. Fig. 2 depicts the whole titanium production process covered by the consortium members. It starts with the sustainable extraction of ilmenite from heavy sands, followed by the patented, low energy-consuming, metallurgical VELTA Ti-Process [US20230132549A1, US11440096B2], and further downstream with metal injection molding, additive manufacturing, and possibly also other powder metallurgical consolidation techniques to produce high-strength, lightweight, and corrosion-resistant titanium materials.
Fig. 1
Geographical distribution of partners within the consortium
Fig. 2
Full process of Ti Powder production covered by the consortium
Fig. 3 illustrates the current value chain of titanium production, which is a demanding path from product design to the end-user. The production processes are highly energy-dependent and have a high ecological carbon footprint. The most common way to produce Titanium powders and their alloys is to combine Kroll and Electrode Induction Melting Gas Atomization (Kroll + EIGA) processes. The Kroll process involves the production of a primary metal, the so-called titanium sponge, from ilmenite concentrate consisting of several stages. The process uses ilmenite concentrate as a feedstock, which is first subjected to a reduction by a smelting process in the presence of a carbon source to produce cast iron and titanium slag. The titanium slag is then chlorinated in the presence of a carbon source to produce titanium tetrachloride. The resulting titanium tetrachloride is refined and reduced with magnesium to produce a titanium metal sponge. The Kroll process for titanium production is a multi-stage, highly energy-intensive method and generates significant waste. Specifically:
First stage: Ilmenite concentrate is melted in the presence of a reducing agent (carbon) to produce titanium slag. By-products such as pig iron and carbon monoxide (CO) are generated during this stage.
Second stage: Titanium slags, containing 80–90% TiO2, are chlorinated to produce titanium tetrachloride (TiCl4). This step results in the generation of various chlorides, including iron chloride and calcium chloride, which constitute waste streams. After neutralization with lime or limestone, approximately 850–1000 kg of solid waste per 1 ton of titanium sponge is produced. These wastes are typically disposed of.
Fig. 3
Current value chain of titanium production
Brief Description of the EIGA Process:
The Electrode Induction Melting Gas Atomization (EIGA) process produces spherical titanium and titanium alloy powders. The process involves:
Melting titanium feedstock (rods) by induction heating under vacuum conditions.
Atomizing the molten metal stream into spherical droplets using a high-pressure inert gas flowing through a ceramic nozzle.
Producing spherical particles typically ranging from 0 to 120 microns.
The EIGA method is highly energy-intensive. Usually, less than 50% of the atomized powder meets the target size specifications per cycle. The off-spec particles typically require re-melting. However, due to complexities associated with titanium recycling, a substantial portion of this waste powder is discarded as scrap.
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Table 1 shows that the total Energy consumption for the Kroll and EIGA Processes combined is about 322 GJ/t produced titanium powder.
TABLE 1
Energy consumption (GJ/t) for titanium powder production [3, 4]
#
Process Stage
Energy Consumption (GJ/t)
1
Raw Material Preparation (GJ/t)
32.22
2
Reductant Production (GJ/t)
62.55
3
Primary Metal Production (GJ/t)
149.54
4
Secondary Processing (GJ/t)
29.29
5
Semi-Finished Shape Production (GJ/t)
19.27
6
EIGA Atomization (GJ/t)
29.52
∑
Total
322.39
The Velta Ti Process, invented and patented by VELTA, is developed to eliminate the disadvantages of the Kroll + EIGA process combination and to achieve advantages in the following areas: (i) Significant reduction in the cost of finished products; (ii) Avoidance of solid and liquid waste generation; (iii) Significant reduction of the carbon footprint; (iv) Improved particle size control of finished powders; (v) Improved homogeneity of alloying additives distribution in alloys.
Fig. 4 depicts the Velta Ti process and the valorization of the resulting by-products. The process starts with the hydrolysis of an aqueous solution of titanium salts to obtain primary particles of crystalline TiO2. The process involves several detailed steps, each contributing to the overall quality and characteristics of the final product:
1.
Precipitation: Dopant oxides or hydroxides are deposited onto titanium oxides or hydroxides by adding dopant salts and then adjusting the pH using either alkaline or acidic reagents.
2.
Calcination: The titanium oxides or hydroxides are subsequently calcined to create a solid solution incorporating the dopant oxides into TiO2. This mixture is milled to powder to serve as feedstock.
3.
Reduction: The feedstock elements are reduced using magnesium and calcium metal.
4.
Formation of Titanium Alloy Powders: Titanium alloy powders with low oxygen grades are formed through further milling, drying, and classification. This process ensures the production of high-quality titanium alloys suitable for various applications.
Fig. 4
Velta Ti process and valorization of by-products
The Velta Ti process significantly reduces the carbon footprint of Ti-alloy powders compared to conventional titanium powder production processes (Kroll + EIGA is considered as the main prototype for conventional processes). Depending on the alloy and the type of powders produced, the Velta Ti process reduces the carbon footprint of titanium compared to conventional processes by 50–80% when using electricity with a medium carbon footprint in both processes.
2 State of the Art Heavy Sand Beneficiation
The Byrzulivske ilmenite deposit is situated in the Kirovohrad region of Ukraine. It is a typical heavy sand deposit with particles smaller than 8 mm. In Fig. 5, a standard borehole sample illustrates the color differences among the various sand layers. Currently, the yellowish initial ore sands are being mined and processed.
Fig. 5
Geological borehole sample
Figure 6 shows the characteristic cross-section of the deposit. The greenish gray layer represents the weathering crust, which consists of altered ilmenite, various iron oxides (limonite, siderite), and primarily clay minerals like kaolinite.
Fig. 6
Cross section of the Byrzulivske ilmenite deposit (UA)
Ilmenite (FeTiO3) can generally be found in various types of deposits, including beach/marine placers and alluvial placer deposits, within other heavy minerals (HMs). Heavy mineral sand deposits can be sedimentary and are usually found along paleo shorelines and in marine placer environments [5, 6]. Heavy sands are primarily mined by dredge, dry, or hydraulic mining. The choice of extraction method mainly depends on factors such as the availability and depth of groundwater, sediment consolidation, and particle size [5, 7]. Comminution is typically unnecessary for these deposits because of the already small particle sizes of the sands [8, 9]. The main processing steps in heavy sand beneficiation are density separation (spirals) and high-intensity magnetic separation (HIMS) [10‐12]. Also, electrostatic separation is crucial in sand beneficiation for low-grade heavy mineral deposits [13‐17].
The current beneficiation scheme starts with sieving steps (# 6 mm and 2.8 mm) and desliming with hydrocyclones to remove particles smaller than 60 µm. With multi-stage gravity separation (Humphrey spirals), the light fraction (mainly quartz sand) is separated from the heavy minerals. The heavy minerals fraction is drained, dried, and further processed with four high-intensity magnetic separation steps with different magnetic flux densities (0.5 T; 0.5 T; 0.6 T; 0.7 T), which produced a concentrate of at least 96% ilmenite grade, achieving a recovery about 85–86%.
Six by-products are produced: three over-screen products, hydrocyclone tailings, a light fraction (quartz sand tailings), and a non-magnetic fraction. All these by-products are currently disposed of in tailings ponds, providing several possibilities for further refining.
3 Project Aims
As part of the dissertation, the distribution of various critical raw materials (particularly rare earth elements, niobium, tantalum, and scandium) will be analyzed. A processing scheme to recover these critical raw materials will be developed and implemented in the existing processing facility. The current beneficiation plant will be optimized to enhance both the grade and recovery of ilmenite concentrates. Additionally, a new approach for the beneficiation of the weathering crust will be tested and evaluated through industrial-scale trials in Ukraine. The purity of kaolinite will be assessed to determine its potential as an additive feedstock for the concrete industry. Further processing of the hydrocyclone tailings using enhanced gravity separation techniques (such as the Mozley gravity separator, Falcon, or Knelson separator) will also be explored.
4 Work Approach
The project consortium is central in defining the overall work approach to ensure a structured and efficient task execution. The project is divided into specific work packages with defined scope and duration. These work packages address key resource assessment, beneficiation, and material utilization aspects.
Figure 7 shows the detailed value chain for titanium production. The Chair of Mineral Processing plays a key role in the sustainable extraction of ilmenite and the valorization of by-products that arise during the processing of ilmenite-bearing heavy sands. The Chair for Nonferrous Metallurgy is accountable for the valorization of by-products during the Velta Ti process.
Fig. 7
Detailed value chain of titanium production covered by the consortium
The Chair of Mineral Processing is also responsible for developing sampling protocols and methodologies for quantifying Critical Raw Materials (CRMs) within all product streams of the beneficiation plant. This will ensure a reliable data collection and assessment, which is essential for the accuracy of the Residual CRM Report. The report will support future mining activities and related projects focused on extracting and processing CRMs.
The current beneficiation processes for initial ore sands will be optimized. This task will also involve the development of a processing scheme for the currently unused weathering crust. Additionally, the inspection and evaluation of residual CRM content in ilmenite ores and their by-products is needed to identify potential opportunities for resource optimization and further processing. Furthermore, the possible use of kaolinite as an additive in concrete production will be evaluated, assessing its effects on mechanical properties and sustainability. Moreover, innovative techniques for processing ultra-fine tailings utilizing enhanced density separation to improve recovery rates and efficiency. In addition to these tasks, the project framework also provides enough space for further individual research efforts, allowing for the exploration of new ideas and methodologies that could complement and enhance the project’s objectives.
Funding
Funded by the European Union under Horizon Europe, grant n. 101177704. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HaDEA). Neither the European Union nor the granting authority can be held responsible for them.
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Processing of Ukrainian Ilmenite-bearing Heavy Sands as a Contribution to Improving Europe’s Self-supply in Critical Raw Materials from Its Own Deposits Presentation of a PhD-Project
Authors
Dipl.-Ing. Michael Lechner Eva Gerold Helmut Flachberger
