Titanium Slag Production Process: Technologies To Improve Efficiency and Sustainability

The starting material for producing titanium and its compounds is titanium dioxide, with relatively few impurities. In particular, this can be rutile concentrate obtained during titanium ores concentration. However, the world’s rutile reserves are somewhat limited, so synthetic rutile or titanium slag, obtained by ilmenite concentrates processing, is more commonly used.

It is a primary commercial (semi-finished) product in the technological chain of obtaining metallic titanium, titanium-based alloys, and highly processed products.

Titanium slag production is commercially feasible due to its high demand in the global market.

The fields of its application are as follows:

1. Approximately 95% of the total production volume is production of titanium dioxide pigment. Further on along the technological chain, it is obtaining white pigment for the pulp and paper industry,  paint and coatings sector, production of synthetic fibers, nanotechnologies, manufacture of rubber products, plastics, heat-resistant and optical glass, white enamel, ceramic dielectrics, and more.
2. About 5% of the total production volume obtains metallic titanium (titanium sponge) and titanium-based alloys. Further along the technological chain, these materials are used in aerospace and rocket engineering, shipbuilding, the chemical industry, electroplating, gas and oil industry, cryogenic technology, mechanical engineering, food industry, medicine, sports equipment, jewelry production, etc.

Titanium is one of the most biologically inert metals. In medicine, it is used for creating prostheses due to its corrosion resistance, lightweight nature, and endurance.

Titanium slag production is accompanied by certain hazardous factors, as with any other metallurgical process. Environmental and personnel safety are achieved through strict adherence to technological standards due to the advantages of titanium slag production with a single-stage method in closed-type ore-thermal furnaces and through extensive use of process automation and control systems, which enable the smelting process to be conducted optimally.

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Titanium slag is a highly demanded product on the market; 95% of it is used to produce titanium dioxide pigment.

There is also a high world demand for inorganic pigments, which is constantly growing. According to experts’ estimations, the share of pigmentary titanium dioxide in the total consumption of inorganic pigments is around 65-70%, and that in the consumption of white pigments exceeds 90% in the last few years.

The aerospace sector is the major consumer of metallic titanium in the market. Most experts emphasize the necessity for further development of its global production.

The industry’s promising future is indicated by the continuous growth of applications of titanium and titanium-based products. Along with the constant application growth of titanium alloys in the aerospace industry (especially in civil and military aviation), titanium is widely used in the construction of desalination plants, oil and gas industry, petrochemicals, medicine, sports, and mechanical engineering.

Deep processing of sponge titanium allows for a significant increase in the product-added value. According to the International Titanium Association, their value can double if titanium ingots are processed into semi-finished products. The value of sports goods increases if compared to ingots by 12-200 times, the cost of automobiles rises by 50-100 times, consumer goods – by 100-800 times, medical components – by 200-10,000 times, and jewelry – by 1,000-10,000 times.

Raw materials for titanium slags production

Titanium is recognized as the ninth most abundant chemical element extracted from the crust of our planet, and its global reserves amount to  0.6% of the Earth’s mass. It often occurs in ore deposits in the form of chemical compounds with iron or oxygen.

Its global market is relatively closed regarding export-import dynamics, with the producing countries also being its primary consumers. The high costs and complexity of its production can explain it.

Mineral raw materials for titanium production

Minerals used for its production are anatase, rutile, ilmenite (containing 52.8% titanium in combination with iron), brookite, leucoxene (a product of ilmenite weathering), arizonite, and pseudobrookite.

Types of deposits of titanium raw materials

Titanium deposits are subdivided into magmatogene, alluvial, and lateritic.

At the moment, about 300 deposits of titanium raw materials are known:

• Alluvial deposits — 230 (69 % of world deposits);
• Magmatic (bed-rocks) — 70 (19,5 %);
• Lateritic — 10 (11,5 %).

At most, 90 of them are explored, primarily alluvial deposits. Regarding mineral composition, ilmenite accounts for 82% of the world’s total metal reserves, anatase – 12%, and rutile – 6%. In terms of mineral ratio, 82% of the world’s total metal reserves accrue to ilmenite, 12% to anatase, and 6% to rutile.

The content of titanium dioxide in titaniferous ores is as follows:

• Rutile – 93-96 %;
• Ilmenite – 44-70 %;
• Leucoxene – 90 %.

Titanium ores undergo beneficiation, resulting in concentrates with an increased TiO2 content. Low-grade ores are enriched using electromagnetic and other methods, producing a concentrate containing up to 50% TiO2 and around 35% Fe2O3 and FeO. Titanium ores are subjected to dressing, resulting in a higher TiO2 content in the concentrate. Poor ores are dressed by electromagnetic and other methods, with the resulting concentrate which contains up to 50% TiO2 and about 35% Fe2O3 and FeO.

Only 5% of all extracted titanium ore is used to directly produce metallic titanium. The remaining 95% are used to produce titanium dioxide pigment and plastics, coloring materials, rubber substances, paper products, and so on.

Our experts share their experience about the process of titanium ore mining and processing.

Major producers of titanium concentrate and metallic titanium

Such countries as the USA, South Africa, Canada, Norway, India, Australia, and Ukraine are in titanium ore (rutile and ilmenite) concentration business. The world’s major titanium sponge producers are the USA, China, Japan, Russia, Ukraine and Kazakhstan.

The leaders in this industry in 2020-2022 were:

1. China, which has the largest deposits of titanium ore. China mines it from magmatogenic and ilmenite-titanomagnetite deposits, producing 22% of the global ilmenite concentrates;
2. Japan;
3. Russia;
4. Kazakhstan;
5. The USA;
6. Australia;
7. Norway;
8. Republic of South Africa;
9. Vietnam;
10. India;
11. Ukraine. Both alluvial and magmatogenic deposits have been explored in the country. Still, only alluvial and near-shore marine deposits located in the northern part of the Ukrainian Shield are actively being developed.

Madagascar and Mozambique have alluvial deposits. Such countries as Canada, Australia, Norway, Chile, and Finland make active geologic explorations. A massive complex of titaniferous deposits was found in Paraguay.

Raw materials for titanium slag production

Titanium slag is obtained from ilmenite concentrates. Ilmenite is a natural mineral containing up to 52.8% titanium in terms of titanium dioxide.

Ilmenite is an association of titanium oxide with iron. Therefore, the first production stage aims to separate titanium dioxide from iron oxides. Ilmenite concentrate is reduced in ore-thermal furnaces (OTF) in the presence of a carbon-containing reductant (wood charcoal, anthracite, coke) to achieve this. 

Technological operations for titanium slag production

A modern, improved technology for titanium slags production through a single-stage method is proposed. This technology is completely ready for implementation.

The process of titanium slag production is the process of smelting ilmenite concentrate in arc ore-thermal furnaces (OTF) in a semi-closed mode with the use of a powder mixture to obtain titanium slag of a specified content of iron oxide, as well as associated metal. 

The most important properties of titanium slags, which determine the reduction smelting process and the ability to fully separate iron and slag and their tapping from the furnace, are meltability, viscosity, and electrical conductivity. 

Obtaining them by a one-stage periodic process includes the following technological operations:

• Transportation, delivery, and storage of raw materials;
• Preparation and charging of the mixture, consisting of ilmenite concentrate, reducing agent, and dust caught in cyclones, into the OTF;
• Reduction smelting of the mixture and obtaining a conditioned melt of slag and associated metal in the OTF;
• Ladle pouring of slag and associated metal;
• Ingot casting;
• Ingot cooling;
• Grinding and magnetic separation of titanium slag;
• Desulfurization, alloying, and carbonization of associated metal;
• Ingot pouring;
• Delivery of titanium slag and associated metal to consumers;
• Recycling of waste energy.

Process flow diagram of titanium slag smelting process

From loading hoppers, ilmenite concentrate and reductant are separately fed to dosing hoppers (position 2-4) through a system of belt conveyors (position 1). Components of the charge are dosed from the dosing hoppers in calculated quantities into a ladle (position 5) placed on a trolley on scales (position 15). 

Filling furnace charge hoppers (positions 61-6) and the reductant hoppers (positions 77-12), used for slag adjustment, are carried out from ladles (position 5), which are transported using an overhead electric crane (position 14). 

Charging the ore-thermal furnace (OTF) occurs from the furnace hoppers through a charging chute. Dust, captured in the cyclones of process GCP of the OTF, is fed into the furnace with the charge.

An afterburner chamber is provided for afterburning the reaction gases (pos. 101-3). Air is supplied to the afterburner chamber by fans (pos. 111-3).

Process gas extraction from the OTF is carried out through a system of gas ducts. Gases are cleaned from dust in cyclones (pos. 12) and bag filters (pos. 13).

Currently, titanium slags production with high TiO2 content (80% and more) has only proven to be feasible and economically viable in ore-thermal furnaces.

Single-stage production has several advantages over other methods of obtaining synthetic rutile. Two-stage one is more difficult as it involves reduction roasting and acid leaching, generates a significant amount of hazardous liquid waste, and requires higher financial investments. Melting synthetic rutile using a single-stage method is promising due to its economic viability (reducing production costs), the possibility of controlling the technological process, and the potential to obtain high-quality products.

Types of charge for reduction smelting in ore-thermal furnaces

For a reduction smelting of ilmenite concentrate in ore-thermal furnaces, two types of charge mix are used – briquetted and powdered.

For better use of the reductant, reduced dust emissions, and reduced specific energy consumption, working with a briquetted charge is advantageous. However, difficulties arise due to the briquettes caking and their cementation by the boiling melt, which disrupts the permeability of the charge. 

Therefore, a combined charge has also been developed in industrial practice, a mixture of briquetted and powdered charges. The ratio between them depends on the type of titanium concentrate. The content of powdered charge varies from 30 to 50%.

Briquettes are manufactured using roller presses, employing sulfide liquor as a binder.

Types of ore-thermal furnaces and requirements for them

For smelting titanium slags, three-electrode ore-thermal furnaces with transformers of the following power are used in the countries of the former USSR (Ukraine, Kazakhstan, Russia):

For better use of the reductant, reduced dust emissions, and reduced specific energy consumption, working with a briquetted charge is advantageous. However, difficulties arise due to the briquettes caking and their cementation by the boiling melt, which disrupts the permeability of the charge. 

Therefore, a combined charge has also been developed in industrial practice, a mixture of briquetted and powdered charges. The ratio between them depends on the type of titanium concentrate. The content of powdered charge varies from 30 to 50%.

Briquettes are manufactured using roller presses, employing sulfide liquor as a binder.

• 5 MVA with charging material quantity up 24 t;
• 16,5 MVA with charging up to 100 t;
• 25 MVA with charging up to 120 t.

Currently, such slags are smelted using open and closed ore-thermal furnaces in a batch process, which involves melting the entire charged material in the furnace and subsequent tapping of smelting products. The periodic nature of the process is driven by the need to obtain synthetic rutile with minimal iron oxides. To achieve this, a reductant is added to the furnace bath at the end of the smelting process. This operation is referred to as slag adjustment.

The periodic process in an open furnace, especially during the slag adjustment phase when the molten slag surface is not covered by solid charge, is accompanied by significant heat losses through escaping gases and radiation from the surface of the melt and the furnace walls.

The use of closed-roof ore-thermal furnaces for smelting slags significantly improves the technical and economic aspects of the process. It is because furnace productivity increases, specific energy consumption decreases, and losses of concentrate (due to the batch carry-over) with outgoing gases are reduced because of a lower amount of generated off-gases (several times less). Additionally, heat losses are reduced.

Several requirements are imposed on synthetic rutile smelting furnaces:

• The furnace should have a relatively high specific power to enable rapid heating of the charge to a temperature around 900-1200°C without its significant melting and to maintain a liquid-flow state of highly viscous slags during the final stage of the process; 
• The electrode diameter and the rate of electrode consumption should be optimized to ensure the required concentration of thermal energy.

Specifications of a 25 MVA ore-thermal furnace

Characteristics of a 25 MVA OTF:

• Type of electrodes – graphite electrodes;
• Electrode diameter – 0,71 m;
• Quantity of electrodes – 3 pcs.;
• Quantity of transformers – 3 pcs.;
• Transformer power – 8333 kVA;
• Weight of charged concentrate for a melting operation – 120 t;
• Furnace top – sectional, water-cooled;
• Cooling medium – circulating process water;
• Two tap-holes for separate tapping of synthetic rutile and associated metal.

Specifications of a reduction smelting process

Tapped titanium slag temperature – 1680 1760o C,  that of the associated metal – 1470-1530o C. Titanium slag weight while tapping – max 18 t.

The technology provides:

1. Furnace production rate  – 62627 t/year;
2. Titanium extraction from the concentrate with the dust recycling into commercial products (titanium slag) not less than 98%;
3. Production of titanium slag of a given composition;
4. Production of the associated standard metal.

Products obtained from smelting ilmenite concentrate in ore-thermal furnaces

As a result of smelting ilmenite concentrates, titanium slags with  TiO2 content ranging from 84% to 90% and FeO content ranging from 5% to 7% are obtained,  depending on the composition of the initial concentrates. 

As a rule, the chemical composition of titanium slags obtained from processing various concentrates and their mixtures undergoes minor variations. It is primarily determined by the completeness of the reduction reactions of iron oxides and the degree of re-reduction of titanium dioxide (TiO2) to lower oxides.

Titanium slags production technology makes it possible to produce them commercially, both for obtaining sponge titanium and for having titanium dioxide pigment using chloride or sulfuric acid methods.

Distribution of major elements between slag and cast iron during charge smelting can be assessed as follows:

• Transfer to slag: titanium – 98.5%, iron – 3.5%, silicon – 72.0%. Part of the silicon evaporates as a lower oxide;
• Transfer to cast iron: iron – 96-97%, titanium – 0.8-1.2%, silicon – 10-12%, vanadium – 45-48%.

Automation of the titanium slag smelting process

The objective of an automation system in the corresponding process is to control and stabilize process parameters of the charge preparation for smelting and to ensure uninterrupted operation of equipment and mechanisms according to a predefined program.

All processes of material transportation, loading and unloading, grinding, classification, dosing and mixing, briquetting, and drying are mechanized and automated.

Automation of the dosing system is designed to provide a rational rate of loading furnaces with a charge of a given composition, coordination, and control of the main parameters of charge materials dosing, their mixing, transportation, and supply to furnace hoppers.

The most significant influence on the ore-thermal furnace efficiency is the automatic control of the electric mode of the smelting process and electrode slipping. The corresponding process automation consists of automatic control of the furnace transformer cooling, water cooling of the furnace top, electrodes slipping, regulation of the top pressure, and other parameters.

Automation of gas cleaning is a crucial factor for the smooth progression of the technological process, ensuring an efficient use of electrical energy and raw materials.

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Guaranteed performance indicators of the proposed technology of titanium slag production in ore-thermal furnaces (OTF)

The proposed technology in ore-thermal furnaces (OTFs) provides for the following:

• Furnace production rate- 62627 t/year;
• Extraction of titanium from the concentrate with recycling dust into commercial products (titanium slag) – no less than 98%;
• Producing titanium slag with a required composition – TiO2 content – 84-90% and FeO – 5-7%;
• Production in the form of a commercial product, which can be used both for obtaining sponge titanium and for producing titanium dioxide pigment using chloride or sulfuric acid methods;
• Production of associated metal;
• Ensuring the process explosion safety and recovery of secondary energy resources.

An automated process control system (APCS) allows for the following:

• To reduce smelting time by 3-5% due to mechanization and automation of dosing and furnace charging;
• To reduce slag “boiling” due to uniform charging across the entire bath area of the furnace, to improve smelting conditions and process control;
• Through automation of the electric smelting process, it’s possible to increase the average hourly power pick-up by 7-9% and reduce smelting time by 6-8%;
• To reduce specific power consumption rate by 50-100 kW per 1 ton of titanium slag and increase furnace production rate by 6-8%.

The M HEAVY TECHNOLOGY country, along with its partners, possesses the necessary human resources to implement projects on modernization and construction of titanium slag production facilities of any size.

We possess:

• Extensive positive experience in titanium slag production with major companies in various countries worldwide, including China, the Republic of India, the Republic of Kazakhstan, the Arab Republic of Egypt, and others;
• Patents and implemented proprietary systems;
• Our technologies.

All projects are performed with the help of BIM.

All critical areas are analyzed utilizing CFD modeling.

We carry out all types of calculations for metallurgical and power units, gas cleaning, water supply, water purification, wastewater systems, etc.

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We perform design works and supply of equipment, installation supervision, and commissioning.

We can perform projects on a «turnkey» basis.

We are able to reconstruct existing ore-thermal furnaces (OTFs) while achieving guaranteed performance indicators.

We make design works in limited and with an ideal price/quality ratio.

 In 100% of cases, the Customer contacts us again for new projects.

Looking for In-depth Engineering Expertise in the Titanium Slag Production Process to Improve It and Gain? Our Professionals are Here to Assist You.

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Titanium slag is a high-demand product in the global market with a significant production volume characterized by a consistent and long-term growth trend.

It is a primary commercial product (semi-finished product) in the technological chain for obtaining titanium dioxide pigment, metallic titanium, titanium-based alloys, and highly processed products. 

It is obtained from ilmenite concentrates in a single-stage method through reduction smelting in ore-thermal furnaces (OTFs).

Depending on ilmenite concentrates composition, titanium slags with TiO2 content ranging from 84% to 90% and FeO content between 5% and 7% are obtained due to the smelting process. These slags are considered commercial products.