Titanium Slag Research Articles

Influence of Theed on strength development and hydration of blended cementitious systems containing titanium slag

A blended cementitious material consisting of cement and titanium slag in a mass ratio of 1:1 was prepared and the influence of varying dosages of tetrakis (2-hydroxyethyl) ethylenediamine (Theed) on the strength development and hydration process of the blended systems was investigated. The hydration process, pore structure and microstructure at different ages were characterised by isothermal conduction calorimetry, X-ray diffraction, thermogravimetric analysis, mercury intrusion porosimetry and scanning electron microscopy. The results showed that: the addition of Theed (0·01–0·10%) tended to improve the flexural and compressive strength of the blended mortars; the addition of Theed increased the hydration degree of the blended cement pastes before 28 d while delaying the early (before 6 h) hydration, as indicated by isothermal calorimetry measurement; the pore structure of the blended cement pastes after curing for 28 d was modified by Theed, which is beneficial for strength development; the pozzolanic reaction of the titanium slag was enhanced by the presence of Theed, as confirmed by the portlandite content, pore structure measurements and morphological observation.

Direct reduction of upgraded titania slag by magnesium for making low-oxygen containing titanium alloy hydride powder

Upgraded titania slag (UGS) is a titanium-rich material with over 90 wt% titanium dioxide and some minor elements such as Fe, Al, Cr, and Si, which is mainly used for preparing TiO2 and TiCl4. In this study, UGS was directly reduced with magnesium powder in a hydrogen atmosphere. Titanium alloy hydride powder with the oxygen content of 0.032 wt% was obtained. The minor elements of Fe, Si, Al, and Cr from the UGS were kept in the final powder with the main phase of TiH1.924(δ), and minor intermetallic phases of HFe2Ti, Ti5Si3H0.9 and Cr1.8TiH5.3. EDS elemental mapping results indicated that HFe2Ti and Ti5Si3H0.9 intermetallics formed bright phase islands in the matrix. The reduction mechanism and the reaction sequence were discussed based on the thermodynamic modelling with the assistance of HSC chemistry software. The possibility of hydrogen reduction of titanium oxides was discussed as well.

Improving the production efficiency of high-titania slag in Ti extraction process: fluxing effect on formation of pseudobrookite

We investigated the carbothermic reduction process of ilmenite ore at 1873 K with flux addition. Without flux, the pseudobrookite phase with a high melting temperature was precipitated during ilmenite smelting. This could be the main reason for decreased reduction of iron in ilmenite. To accelerate reduction of ilmenite, two factors were considered. One is increasing the reduction driving force during smelting. Activity of FeO is the major factor to control reduction in driving force. The other factor is delay in formation of the pseudobrookite phase, a high-melting point precipitation phase. In this system, MgO in ilmenite could be used to form pseudobrookite. To control these factors, in this study, flux agent (i.e., Na2O or SiO2) addition was considered. The thermochemical simulation program, FactSageTM7.0 was used to calculate the viscosity of slag and the activity of components as fluxing agents were added. High-temperature experiments using an induction furnace were also conducted to confirm the computational results. To determine the composition of final products, i.e., titanium slag, X-ray fluorescence analysis was executed. As a result of Fe and Ti behaviours in slag, SiO2 addition showed no significant difference from the slag without flux. However, Fe reduction in ilmenite, i.e. TiO2-enrichment, was more accelerated when Na2O was added. X-ray diffraction, scanning electron microscopic and transmission electron microscopic analyses results also showed that even 1 wt% Na2O addition significantly influenced the titanium slag production compared to no flux addition.

Material flow analysis of titanium dioxide and sustainable policy suggestion in China

Titanium dioxide is a significant white inorganic pigment used in coating, plastic, rubber, ink, paper, etc. Material flow analysis of TiO2 can help to analyze the relationship among inflows, outflows and stocks throughout the whole titanium life-cycle in China. This paper divides the whole material flow of TiO2 into four stages by using MFA, including primary production, manufacturing and fabrication, use and waste management. The results indicated that China produced 2,654,700 tons of TiO2 in 2017, which about 95% of the TiO2 comes from the sulfuric acid method. 70% TiO2 is used for domestic consumption which 85% is low-end products such as coatings, plastics and paper. Because of the low recovery rate of TiO2 products and the low efficiency of the sulfuric acid process method, the waste of titanium resources is serious. The policy suggestions for improving the resource utilization efficiency of TiO2 are as follows: increasing the proportion of the sulfuric acid purification of high titanium slag, and promoting the proportion of chlorination process to produce TiO2; the government should strengthen the protective development of ilmenite resources in the “fourteenth five-year plan” of China's mining industry, and adjust China's titanium industrial structure and gradually develop into high-end fields.

Optimization of Basicity of High Ti Slag for Efficient Smelting of Vanadium Titanomagnetite Metallized Pellets

Slag basicity (mass ratio of CaO to SiO2) is an important index to ensure smooth operation and efficient separation between the metal and slag within the metallurgical industry. Effects of basicity of the high titanium slag on the recovery of iron and vanadium, the separation behaviors between iron and slag, as well as the slag foaming behavior during the smelting process with the operating temperature of 1550 °C have been experimentally investigated. The results show that the recovery ratios of iron and vanadium increase with higher slag basicity. The amount of dispersed metallic iron droplets in the slag decreases sharply when the basicity increases from 0.5 to 0.8, then decreases slowly when the basicity is from 0.8 to 1.1. Furthermore, the perovskite (CaTiO3) phase appears when the basicity is above 0.8. The foaming height is at a high level when the basicity is from 0.5 to 0.6, then it decreases when the basicity is increased from 0.6 to 0.7, whereas it slowly increases with higher slag basicity. Finally, the optimum basicity range of titanium slag for efficient smelting of vanadium titanomagnetite is proposed to be 0.8 to 1.1 by considering the combined effects on the recovery, foaming, and minimization on the retention of the metal droplets within the slag.

Hydraulic Activity and Microstructure Analysis of High-Titanium Slag.

To explain the relationship between the hydration activity of high-titanium slag and its microstructure, the hydration activity of high-titanium slag was determined, then the mineral phase and microstructure characteristics of high-titanium slag glass phase and blast furnace slag were investigated using a series of analytical methods, which contain X-Ray Diffraction (XRD), Scanning Electronic Microscope (SEM), Fourier Transform Infrared spectroscopy (FTIR), Raman spectroscopy, and Nuclear Magnetic Resonance spectroscopy (NMR). The results showed that in slow-cooled high-titanium slag, the hydration inert mineral content was about 98%, and the glass phase content was less than 2%, hence, the hydration activity of slow-cooled high titanium slag accounted for less than 25% of that of the blast furnace slag. The content of the glass phase in water-quenched high-titanium slag was 98%, but the microstructure of the glass phase was very different from that of the blast furnace slag. The glass phase of high-titanium slag has stable forms, which are TiO44− monomers, chain or sheet units O–Ti–O, and a small amount of 6-coordination Ti4+. The Ti makes the SiO4 tetrahedron in a glass phase network not only a monosilicate, but more stable forms of disilicates and chain middle groups also appeared. The relative bridge oxygen number increased to 0.2, hence, the hydration activity of water-quenched high-titanium slag took up less than 37% of that of the blast furnace slag.

Mechanism of Melt Separation in Preparation of Low-Oxygen High Titanium Ferroalloy Prepared by Multistage and Deep Reduction

A novel method to prepare low-oxygen and high-titanium ferroalloy by multistage and deep reduction was proposed in this study. Specifically, the raw materials, high titanium slag and iron concentrate are firstly reduced by insufficient Al powder to obtain high temperature melt. Secondly, CaO and CaF2 are added into the melt to adjust the basicity of the molten slag. Then, a melt separation under the heat preservation is carried out to intensify the slag-metal separation. Finally, calcium or magnesium is added into the metal melt for a deep reduction. Thereafter, high titanium ferroalloy with an extra-low oxygen content can be obtained. Effects of slag basicity and melt separation time on the slag-metal separation removal were systematically studied. The results indicate that the high titanium ferroalloy, produced by the thermite method, contains a lot of Al2O3 inclusions. This leads to a high oxygen and aluminum content in the alloy. With a melt separation with high basicity slag treatment, the Al2O3 inclusions can be effectively removed from the alloy melt, and the slag-metal separation efficiency is greatly improved. With the addition of high basicity slag during melt separation, Ti content in the alloy is improved from 51.04% to 68.24%. Furthermore, and the Al and O contents are reduced from 10.38% and 9.36% to 4.24% and 1.56%, respectively. However, suboxides, such as Ti2O and Fe0.9536O, still exist after a melt separation. This indicates that a deep reduction is needed to obtain extra-low oxygen high titanium ferroalloy.

Simultaneous removal of Cr(III) and V(V) and enhanced synthesis of high-grade rutile TiO2 based on sodium carbonate decomposition

Rutile TiO2 is widely applied as the raw material to produce titanium dioxide and titanium sponge, whereas the Cr (III) and V (V) impurities in rutile TiO2 significantly affect the performance of related products. In the present work, the sodium carbonate decomposition treatment on Panzhihua titanium slag was attempted, to improve the preparation process of rutile TiO2 with high crystallinity and simultaneously reduce the chromium (Cr) and vanadium (V) content as hazardous elements. Effects of sodium carbonate decomposition treatment on the crystal composition, microstructure of rutile TiO2 were determined using XRD, SEM and Raman characterization. The recovery of Cr(III) and V(V) was achieved through leaching the roasted titanium slag by dilute sulfuric acid, with the chromium and vanadium content in the residue decreasing up to 0.03 % and 0.04 %, respectively, followed by the final product rutile TiO2 was produced by the leaching residue calcined at 1323.15 K with a duration time of 120 min, with 85.56 % of TiO2 grade. The work highlights the feasibility of synchronously preparing rutile TiO2 and removing hazardous Cr (III) and V (V) impurities from titanium slag using sodium carbonate decomposition.

Synthesis of rutile TiO2 powder by microwave-enhanced roasting followed by hydrochloric acid leaching

In this paper, the preparation of rutile TiO2 powder from titanium slag by microwave-assisted activation roasting followed by hydrochloric acid leaching was investigated. The effects of the additive Na2CO3 on the crystal form, cell, crystallinity, phase transformation, surface functional groups and micro-surface structure of the calcined product were systematically studied using X-ray powder diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The results confirmed that the strongest characteristic Raman bands of rutile TiO2 and the weakest FT-IR bands of (CO3)−2 were found when the Na2CO3 mass ratio was 0.4. Accordingly, the crystallinity for the product, namely short rod structure rutile TiO2 powder, reached its peak value of 99.21% with a corresponding average grain size of 43.5 nm. The excessive Na2CO3 was found to be disadvantageous for the crystallinity of the product, since it formed a coverage on the surface of titanium slag which prevented the oxidation reaction for the decomposition of anosovite.

Preparation of alternative raw materials for resource development to use in Indian ferro alloy and steel industrial applications

The present paper deals mainly with iron bearing titania enriched ilmenite raw mineral, its production, exports and imports and consumption of Ferro alloy industries. This paper not only reveals the recovery of iron from iron bearing titania mineral ilmenite with physical beneficiation methods but also gives the process of preparation and separation of titania slag and iron metal by using microwave heat treatment. The process of recovery of iron as a by-product from ilmenite mineral, which abundantly available along the coastal line of India, is economical and by which the conservation of some higher grade iron ores of the country will be possible for future. The products obtained from this process can be treated as alternative raw materials resources for steel and iron making industries.

The influence of basicity and TiO2 on the crystallization behavior of high Ti-bearing slags

The change of basicity or TiO2 content in the high titanium slag will promote the evolution of the type and size of the precipitated crystal of the titanium-rich phase.

Two-phase technology of titanium slag production from ilmenite concentrates

Titanium slag is a basic raw material for production of titanium dioxide, widely used in various branches of national economy. Titanium slag is produced out of ilmenite concentrate. In Russian Federation there are several ilmenite deposits of ledge and placer type under various stages of development. Laboratory studies of ilmenite concentrates of Malyshevskoye, Irshanskoye and Medvedevskoye deposits processing technologies carried out. Two-phase technological scheme proposed, including ilmenite-coal briquettes reducing in an annular furnace and smelting of hot metallized briquettes in an ore-smelting furnace resulting in titanium slag and pig iron obtaining. Ilmenite concentrates were mixed with anthracite, bonding agent, briquetted and reduced in an annular furnace. After reducing the hot metallized briquettes were smelted in an electric furnace at 1650 ° С and the smelting products were casted into molds. The chemical and size composition of ilmenite concentrates and chemical composition of metallized briquettes presented. Technical indices of the annular furnace operation at metallized briquettes production and chemical composition of titanium slag and pig iron obtained out of the mentioned deposits ilmenite concentrates cited. It was determined, that the production of briquettes with high degree of metallization in the annular furnace is possible at heat treatment mode, providing a quick heating until the temperature of 1400-1500 °С. The cycle of the briquettes heat treatment in the annular furnace can be 15-30 min, including the phases of charging, heating, roasting, cooling and discharging. To study the heat treatment parameters effect on the process of coal-thermal reducing of ilmenite concentrates briquettes, a heat-physical model was elaborated. The model was based on studies of coal-thermal reducing kinetics of briquettes comprising ilmenite and anthracite, as well as zonal heat and material balances of oxidizing-reducing processes in the annular furnace. A technological scheme of titanium slag from ilmenite concentrates of Malyshevskoye, Irshanskoye and Medvedevskoye deposits proposed.

Fabrication of Mg doped magnetite nanoparticles by recycling of titanium slag and their application of arsenate adsorption

Abstract To ease environment pressure and improve the comprehensive utilization of titanium slag, Mg doped magnetite nanoparticles (MFNPs) fabricated by recycling of titanium slag via solid-phase reduction roasting technology were used as an adsorbing material for treating As(V)-polluted water, and investigated by various analytical techniques. The analysis of the X-ray photoelectron spectroscopy revealed that As(V) ions were partially reduced to As(III) ions by the Fe(II)-MFNPs, and then As(III) and As(V) were adsorbed on the MFNPs through electrostatic attraction, and simultaneously fabricated Fe–O–As via surface complexation. The investigation of As(V) adsorption process on the MFNPs indicated that the as-received equilibrium relationship was well depicted by the Friendlies isotherm model, and the maximum loading capacity of As(V) estimated from Langmuir isotherm model was 33.71 mg/g at ambient temperature. Moreover, the adsorption of As(V) on the MFNPs was accorded with pseudo-second-order kinetic model. The thermodynamics functions manifested that adsorption of As(V) on the MFNPs belonged to spontaneous chemisorption. Desorption of the As(V)-MFNPs was easily performed, with repeated use for at least five cycles. These results indicated that the fabricated MFNPs by reduction roasting technology was functioned as an environmentally friendly adsorbent with promising prospects for arsenic removal from contaminated water.

Research on mining filling material prepared by high titanium metallurgy waste residue

Using the vanadium titano-magnetite for iron-making, the steel enterprises have discharged water-quenched Ti-bearing slag. Due to the high titanium content, low activity and difficult-to-use characteristic, there are vast amount of high titanium slags, which not only occupies the land, but also causes resources wasting and environment polluted. This paper analyzed the chemical component, microstructure, grindability, activity index and other factors of high titanium slag and studied the mining filling material prepared by high titanium slag. The results show that the main chemical components of high titanium slag are similar with the ordinary slag. Both of them consist of CaO, SiO2 and Al2O3, all of which account for about 80% of the total weight. However, the content of TiO2 accounts for 8.4%, which is much higher than that of ordinary slag. Therefore, the grindability of TiO2 is poor. The solid waste cementitious material was prepared by slag, flue gas desulfurization gypsum and high titanium slag, whose specific surface area was 530 m2/kg. After the maintenance for 28 hours, the compressive strength of this material reaches 3MPa.

Preparation and properties of reactive powder concrete by using titanium slag aggregates

In this research, titanium slag (TS) was used as an alternative aggregate to prepare reactive powder concrete (RPC). The mechanical properties, hydration characteristics, and interface structure of the RPC was investigated. The results showed that the porous, low-activity TS aggregate had high water adsorption and proper secondary hydration during moulding and hardening. This accelerated the early-age hydration reaction of RPC and significantly improved the interfacial structure between paste and aggregate. Ca2+, Mg2+, and Si4+ present in TS leached out and generated additional C-S-H around the aggregate during hydration, which filled the gap between paste and aggregate

Production of ferrotitanium alloy from titania slag based on aluminothermic reduction

At present, the titanium resource from vanadium-titanium magnetite (VTM) has not been used very effectively. With the aim of addressing this urgent problem, the titania slag with over 40 wt% TiO2 was obtained from VTM through gaseous reduction and melting separation in the previous work. In this study, the aluminothermic reduction for the ferrotitanium alloy production was conducted in order to develop a new utilization way for the titanium resource from VTM. CaO and Fe2O3 are extra added to ensure the slag fluidity, alloy quality, and sufficient physical heat. And the addition ratios of Al are optimized by the thermodynamic calculation. At last, the ferrotitanium alloy with 30.5 wt% Ti, 8.4 wt% Al, 3.2 wt% Si content is successfully prepared. However, the macro analysis indicates that some alloy particles with different contents are dispersedly distributed among the slag, and the slag consists of three different phases. It is mainly associated with the reaction intensity and thermodynamic stability, which is detailedly discussed in this paper as well.

A Clean Process to Prepare High-Quality Acid-Soluble Titanium Slag from Titanium Middling Ore

A direct reduction-magnetic separation-alkali leaching-dilute acid washing method was proposed to prepare high-quality acid-soluble titanium slag (HQASTS) from titanium middling ore. The relevant potential pH diagrams were built, and the analysis results showed that the pH values for alkali leaching and dilute acid washing should be higher than 13.50 and lower than 1.00, respectively. Increasing temperature was beneficial to alkali leaching but not to dilute acid washing. The effects of operating parameters on the TiO2 content and impurity oxides extraction ratios of titanium slag were investigated, and the optimal experimental conditions were obtained. The HQASTS was obtained with TiO2 and Fe2O3 content of 75.37 wt % and 0.96 wt %, respectively, under the above conditions. Furthermore, the leaching mechanism was studied by chemical analysis and X-ray diffraction (XRD) technology, and it was found that the alkali leaching-dilute acid washing process presented in this work could avoid the encapsulation of the unreacted anorthite by the calcium aluminum spinel generated in alkali leaching.

Vacuum Electromagnetic Levitation Melting of Ti–Al Based Alloy Prepared by Aluminothermic Reduction of Acid Soluble Ti Bearing Slag

A Ti-Al based alloy was prepared by aluminothermic reduction of acid soluble titanium slag followed by electromagnetic levitation refining. It was observed from the XRD and microstructure analysis that the alloy after refining was mainly composed of TiAl2 phase, with Mn and Fe dissolving into Al lattice, Ti5Si3, TiAl, and other metallic compounds. With increase of the vacuum degree or refining time, the phase of the alloy changed from an Al-rich compound to a Ti-rich phase due to Al loss by evaporation. The kinetics of Al evaporation demonstrated that the rate determining step of Al evaporation was controlled by the mass transfer in the liquid metal phase. The oxygen removal showed increasing tendency with increase of vacuum degree and refining time. The removal rate of oxygen after refining at 1858 K, 400 Pa for 25 min was over 40% and the final percentage of oxygen in the alloy was 0.59 wt%. Vickers hardness of the alloy showed increasing tendency with increase of vacuum degree and refining time, while its bending strength showed decreasing tendency. These results are mainly attributed to the comprehensive effect of oxide inclusions removal and phase transition in the refining process.

Experimental Study on Axial Compression Behavior and Bearing Capacity Analysis of High Titanium Slag CFST Columns

In order to study the axial compression behavior of concrete-filled steel tubular (CFST) columns filled with high titanium slag, a total of 32 specimens, including normal CFST columns, half-high titanium slag CFST columns, and full-high titanium slag CFST columns, were used as experimental samples in this study. The axial compression behaviors of high titanium slag CFST columns and normal CFST columns with various parameters such as length–diameter ratio, strength grade of concrete, strength grade of steel tube, steel content ratio, etc., were evaluated and compared through axial compression testing under monotonic static loading. The results showed that the axial compressive behaviors of high titanium slag CFST columns with various length–diameter ratios were not significantly different from those of normal CFST columns, both of which showed good axial compression performance. In addition, the length–diameter ratio limit between short and medium long column was from 3.5 to 4.4. The length–diameter ratio was the main factor influencing the shape of load–deformation curve of CFST columns. The casing hoop coefficient also had a great influence on the bearing capacity of short columns, while the influence on that of middle and long columns was not obvious. In the end, the bearing capacities of all specimens were calculated by bearing capacity formulas in European EC4, American AISC360-10, and Chinese GB50936-2014 standards. The calculated values were in good agreement with the test results.

Flotation behavior and adsorption mechanism of salicylhydroxamic acid in artificial mineral anosovite

Flotation is often employed to separate valuable natural minerals and gangue minerals. However, few studies have been conducted on artificial mineral flotation. Anosovite, the primary mineral in titanium slag, is a typical artificial mineral that can be enriched by flotation. In the present work, flotation behavior and adsorption mechanism of anosovite in salicylhydroxamic acid (SHA) solution were studied. The influence of pH and SHA dosage on anosovite flotability was investigated. Micro-flotation test results show that a pH range of 7–8.5 is available for SHA to collect anosovite. A maximum recovery of 93.26% can be obtained with SHA dosage of only 4×10−5 mol/L. In addition, TOC, zeta potential, FTIR, SEM-EDS, and XPS analyses were used to study the adsorption mechanism. Results demonstrated that SHA adsorption is governed by chemisorption. XPS studies further suggested that chemical adsorption occurred at the Ti sites on the anosovite surface.