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The dissolution behaviors of various minerals in the tellurium–bismuth ore during oxidic–acidic leaching were investigated systematically in this work. The Te–Bi phase in the ore distributes in network shape, triangular shape, tree shape, strip shape, bulk shape, sparse granule, flake shape, crescent, etc., which are closely intercalated with FeS, FeS2, and CaCO3·(Mg,Fe,Mn)CO3. Under suitable conditions, 95.61% Te and 95.77% Bi can be recovered. Within 20 min of the initial leaching, most of dolomite and Te–Bi phase dissolve rapidly. With the extension of leaching time, a large amount of rod-shape CaSO4 particles form, attach on the surface of the tellurium–bismuth ore particles, and then grow and coarsen. The (Mg,Fe,Al)(Si,Al)Ox(OH)y phase dissolves mainly within 60 min. Fe–S phase can be corroded but cannot dissolve completely. SiO2 cannot dissolve at all. Besides, H2SO4 and Fe3+ play a significant role on the dissolution of various minerals in the ore. Without Fe3+ or H2SO4 in immersion liquid, Te and Bi are difficult to be leached into the lixivium from the tellurium–bismuth ore. As H2SO4 concentration and Fe3+ concentration increase, Te–Bi phase and Fe–Mg–Al–Si–O phase gradually dissolve, the Fe–S phase can be corroded obviously but cannot dissolve, and the Si–O phase has no change. The dissolution of dolomite is mainly controlled by H2SO4. The dissolution behaviors of various minerals in the tellurium–bismuth ore during oxidic–acidic leaching were investigated systematically. Most of dolomite and Te–Bi phase dissolve rapidly. A large amount of rod-shape CaSO4 particles form, attach on the surface of the tellurium–bismuth ore particles, and then grow and coarsen. H2SO4 and Fe3+ play a significant role on the dissolution of various minerals in the ore.

Magnesium vanadates are important chemical products for luminescent materials and energy storage and also important intermediate substances during vanadium extraction, whose solubility behavior is, however, ambiguous and controversial. In this work, three common magnesium vanadates, namely, magnesium ortho-, pyro-, and metavanadate, were synthesized by a solid–solid synthesis method with MgO and V2O5 as raw materials. In optimum synthesis conditions, the obtained pure magnesium vanadates are confirmed using x-ray diffraction analysis. Then, their solubilities in water and in acidic solution in the pH range of 0–7.0 were systematically investigated at different temperatures. Results show that magnesium vanadates are readily soluble in acidic solution but are only slightly soluble in water, while in both cases magnesium metavanadate has higher solubility than orthovanadate and pyrovanadate. This work provides the fundamental data to improve understanding of the vanadium extraction mechanism and the performance control of magnesium vanadate materials.

In order to effectively improve the environmental problems caused by steel slag stacking, the air-quenching process of molten steel slag was carried out, and the properties of the air-quenched steel slag (AQSS) has been investigated by various characterization methods. The results show that the main phases of AQSS were Ca2SiO4, RO phase (solid solution formed by MgO, FeO, and MnO) and Ca2Fe2O5. The AQSS met the technical requirements of a sandblasting abrasive. In addition, the Rockwell hardness of the AQSS with particle size of 1.0–3.0 mm exceeded 50.00 HRC. The particle size of 1–2.5 mm was particularly adapted to use as a sandblasting abrasive. It is clear that AQSS can be used as a sandblasting abrasive by analyzing and comparing the particle size and hardness of the AQSS and commonly used sandblasting abrasives.

The fusion of the leaching and purification processes was realized by directly using microemulsion as the leaching agent. The bis-(2-ethyhexyl) phosphoric acid (DEHPA)/n-heptane/NaOH microemulsion system was established to directly leach vanadates from sodium-roasted vanadium slag. The effect of the leaching agent on the leaching efficiency was investigated, in addition to the molar ratio of H2O/NaDEHP (W), DEHPA concentration, solid/liquid ratio, stirring time, and leaching temperature. In optimal situations, the vanadium leaching efficiency reaches 79.57%. The X-ray diffraction characterization of the leaching residue and the Raman spectrum of the microemulsion before and after leaching demonstrate the successful entry of vanadates from the sodium-roasted vanadium slag into the microemulsion. The proposed method successfully realizes the leaching and purification of vanadates in one step, thereby greatly reducing production costs and environmental pollution. It also offers a new way to achieve the green recovery of valuable metals from solid resources.

Based on two considerations of making full use of the residual heat of vanadium slag and exploring a novel green vanadium extraction process, this article employs vanadium slag with high MgO content as raw material, blowing oxygen into the molten vanadium slag and using the residual heat of the vanadium slag to carry out high-temperature roasting experiments. XRD and SEM/EDS were used to characterize the phase evolution and morphology of vanadium slag with high MgO content during oxidation. The results show that at a high temperature of 1723 K, the trivalent vanadium in vanadium slag can be partly transformed into acid-soluble pentavalent vanadium. Titanium-bearing spinel was oxidized into a large amount of strip pseudobrookite Fe2TiO5. After oxidation, vanadium existed in the form of the solid solution of magnesium pyrovanadate (Mg, Mn, Ca)2V2O7. The leaching rate of roasted vanadium slag with high MgO content is significantly higher than that of industrial vanadium slag. With the increase of oxygen blowing time from 10 to 30 minutes, the leaching rate of roasted vanadium slag with high MgO content increases from 23.19 to 53.69 pct.

This article investigated the saturated solubility of MgO in converter vanadium slag and its influencing factors. The experimental results of MgO dissolution equilibrium are consistent with the theoretical calculation results. The results show that in MgO saturated vanadium slag, MgO mainly exists in MgV2O4 and MgSiO3. The increase of V2O3 content or the decrease of the FeO/SiO2 ratio is beneficial to increasing the saturated solubility of MgO in the FeO-SiO2-V2O3 slag system. The saturated solubility of MgO in vanadium slag increases from 7.5 to 8.0 wt.% when the temperature increases from 1633 to 1753 K. In addition, the solubility of MgO also increases with the increase of TiO2 and Al2O3 content and decreases with the increase of MnO content.

The chromium valence states in the CaO–SiO2–FeO–MgO–CrOx system were investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that the XPS peaks of Cr 2p3/2 and Cr 2p1/2 locate at the binding energy of ∼577 and ∼586 eV, respectively. There are three kinds of chromium ions such as bivalent Cr(ii), trivalent Cr(iii), and hexavalent Cr(vi) in the CaO–SiO2–FeO–MgO–CrOx slag. Cr(iii) is the dominant valence state, and more than 77.99% Cr is trivalent Cr(iii). The fraction of Cr(ii)/Cr is in the range of 11.24–17.22%. The fraction of Cr(vi)/Cr is below 4.80%. The fraction of Cr(ii)/Cr decreases with increasing slag basicity, Cr2O3 content, temperature, or oxygen pressure log(PO2), while the fraction of Cr(iii)/Cr increases with increasing basicity, Cr2O3 content, temperature, or oxygen pressure. The trend of change is opposite. Low log(PO2), high Cr2O3 content, and high temperature are beneficial to reduce the toxic hexavalent Cr(vi). The slag basicity has little influence on the fraction of Cr(vi)/Cr.

Rechargeable magnesium batteries (RMBs) suffer from low capacity and poor cyclability of cathode materials, which is due to the sluggish Mg

Aiming at the high-efficiency utilization of vanadium–titanium magnetite with high chromium content, a slag formation path in the converter smelting process of semi-steel containing chromium was pr...

Polyoxometalates (POMs) are intriguing catalysts for various reactions. However, the function of their counter-cations is overlooked. Here, we show that flexible counter-cations of methyltrioctylammonium can trigger polyoxovanadates to transform from octahedrally coordinated H2V10O284- to tetrahedrally coordinated V10O262-. This structural transformation enhances the performance tunability of POM chemistry and improves catalyst design.

Vanadium(V) valence analysis is of great significance to the vanadium recovery and environmental safety of the vanadium extraction industry. The stability constants and stereo structures of complexes between EDTA and vanadium ions with various valences are only roughly estimated, which hinders the development of vanadium valence analysis. This work investigates in detail the complexation behavior of V(IV) and V(V), the most common valences in aqueous solution, with EDTA. The stability constants of [VO(EDTA)]2− and [VO2(EDTA)]3− complexes are determined to be 107.03±0.14 and 105.47±0.25 at pH 6, respectively. First-principles calculations reveal that the stereo structure of the [VO(EDTA)]2− complex is comprised of three 5-membered rings while that of the [VO2(EDTA)]3− complex is comprised of one 8-membered ring, which calls for the reconsideration of V–EDTA structures assumed commonly. This work has corrected the assumed stability constants and stereo structures of V–EDTA complexes and provided the essential knowledge to develop vanadium valence analysis in the vanadium industry.

A novel strategy for comprehensive utilization of vanadium slag with high-content chromium is proposed in the present study. This approach involves two steps: vanadium slag is first treated by the ...

The ferrosilicon nitride used for steelmaking has been synthesized by direct nitriding. The relationship between the reaction temperature and nitriding effect was investigated. The results show that the initial reaction temperature between FeSi75 and nitrogen is approximately 900°C. Increasing holding temperature or prolonging holding time is beneficial to increase the nitrogen content in the nitrided product. At 1400°C, the nitrogen content in ferrosilicon nitride reached 30.28% when the holding time was 4 h. With the increase of nitriding reaction temperature, the phase of α-Si3N4 transferred to β-Si3N4 gradually. Pore diffusion was identified as the dominant restrictive link during the ferrosilicon nitriding process.

The high-chromium vanadium slag is treated by magnesium roasting-acid leaching to obtain Cr-containing tailings, which are not the solid waste but important valuable resources for various fields. In order to extract Cr from these tailings, sodium carbonate as annexing agent mixed tailings was roasted and then leached by water. There are several factors that were investigated including roasting temperature, roasting time, the molar ratio of Na/(V+Cr), leaching time, leaching temperature, and the ratio of L/S. The Cr-containing tailings before and after roasting and the residue after leaching were characterized by XRD. It is indicated that Cr in tailings was all entered into leaching solution due to residue not found Cr-containing phase. Under the optimal conditions, the maximum leaching rate of Cr was 92.49%.

Based on two considerations of making full use of the residual heat of V-slag and exploring a novel green V extraction process, this paper employs MgO as the roasting additive, blows oxygen into the molten V-slag, and uses the residual heat of the V-slag for pre-roasting at high temperature. The influence of MgO on the phase structure of V-slags during oxidation has been investigated by XRD and SEM/EDS. The result shows that MgO as the roasting additive can convert V-slag at a high temperature of 1723 K. With the increase of blowing time of oxygen, the trivalent V in the spinel phase gradually disperses in the silicate matrix and then concentrates in the form of magnesium vanadate solid solution (Mg, Mn, Ca)2V2O7. Furthermore, with the increase of MgO content, the peak intensity of the Mg2V2O7 diffraction peak increases significantly. When the MgO content in V-slag increases from 4.01 to 12.74 wt%, the extraction efficiency increases from 18.99 to 64.07%.

The physical and mathematical model of molten converter slag particle has been established in this paper. The laws of solidification and heat transfer of molten converter slag particles with the diameter of 2 mm in the process of air quenching granulation at different air velocity have been simulated by FLUENT, which the conclusion is as follows: the transformation order of molten converter slag particles is upwind point → upper point and lower point → leeward point → center point. When the air velocity is 200 m/s and 1 m/s, the time of temperature maintaining phase transformation at the center point is about 0.5 s and 1 s, respectively. Under the conditions of forced cooling and natural cooling, the maximum value of internal temperature difference of converter slag particles is reached after 0.5 s and 2 s, respectively. When v = 200 m/s and v = 1 m/s, the internal maximum temperature differences of converter slag particles were 645 K and 162 K, respectively. Moreover, the maximum internal temperature point is deviated to the right with different cooling conditions. When the air velocity was 200 m/s and 1 m/s, the starting solidification time was 0.05 s and 0.35 s, respectively, and it severally took 0.55 s and 1.80 s to complete the solidification.

Chromium sludge is a hazardous solid waste which cannot be effectively treated but only piled up and abandoned, causing serious environment pollution and resource wasting. This work proposes an effective novel process to separately recover all resources in chromium sludge via a sustainable way. The obtained acid solving liquid from chromium sludge is desiliconized by cationic flocculant (PCAM) to induce coprecipitation of polysilicate gel and PCAM, which mixture is calcinated to generate the product of white carbon black in purity of 94.35% with a recovery of 92.58%. After desiliconization, V in the solving liquid is selectively extracted by microemulsion (ME), which is recovered as V2O5 in purity of 99.34% with a recovery of 95.53% by the subsequent procedure of stripping-precipitation-calcination. The Fe3+ in raffinate is reduced to Fe2+ cations by Na2SO3, and is then recovered by H2C2O4 precipitation to generate the FeC2O4 product in purity of 99.12% with a recovery of 98.25%. Cr3+ cations in residual solution are recovered by alkaline precipitation and calcination to generate the Cr2O3 product in purity of 98.25% with a recovery of 92.68%. This work provides fresh penetrations into the synchronous detoxification, resource recovery and value-added utilization of hazardous industrial solid wastes.

Dephosphorization during the vanadium extraction process in the converter was studied. The effects of the slag basicity and FeO content on the dephosphorization and the mineral phases in the phosphorus-containing vanadium slag are discussed. The results show that removal of phosphorus from the hot metal during the vanadium extraction process can be achieved by adding lime into the vanadium extraction converter. The highest dephosphorization rate was obtained at slag basicity of 1.93. The phosphorus distribution ratio increased with increasing FeO content up to 16–18% but decreased thereafter. Vanadium was present in the slag only as spinels rather than calcium vanadate. Phosphorus was still present in the form of calcium phosphate eutectic in calcium silicate. The present work proves that the vanadium extraction and dephosphorization processes are nonconflicting reactions.

MD simulations have been accomplished to study the transport properties of molten CaO-SiO2-P2O5-FeO system. The self-diffusion coefficients of Ca, Si, P, Fe and O ions increase with increasing slag basicity and FeO content, while decrease with increasing P2O5 content. The diffusivities of these ions in the quaternary melts follow the sequence of Ca>Fe>O>P>Si. The calculated viscosities are in good agreement with the experimental ones. It is obvious that increasing the amount of network formers (e. g., Si and P ions) leads to larger viscosity and degree of slag polymerization, while adding network modifiers (e. g., Fe and Ca ions) causes viscosity and slag polymerization to decrease. Except for the calculation, the FT-IR analysis also confirmed the relationship between structural properties of the slag and composition. The viscosity of the slag increases linearly with increasing the parameter of Q(Si+P).

Dephosphorisation is of great significance for the recycling of steel slags in iron and steel industry. In this paper, the dephosphorisation of steel slags by leaching with sulphuric acid was inves...

The structural properties of molten CaO–SiO2–P2O5–FeO slag system with varying slag basicity have been investigated by molecular dynamic (MD) simulations using the pairwise potential model. The result shows that more than 95 % Si and 98 % P are four coordinated and form tetrahedral structures. Non-bridging oxygen occupies a predominant position in the system. With basicity increasing from 0.6 to 1.5, the proportion of non-bridging oxygen increases from 66.3 % to 77.3 %, whilst the bridging oxygen decreases from 30.1 % to 10.2 %. Both the result of MD simulations and Raman spectroscopic analysis show the proportion of Q0 increases with increasing slag basicity, whilst Q2 and Q3 decrease. The degree of polymerization of CaO–SiO2–P2O5–FeO system decreases with increasing slag basicity.

Slag splashing is the most effective technology to improve the furnace campaign of converter; however, due to the great difference of composition between the vanadium slag and the steel sla...

A rotary viscosimeter and Raman spectrum were employed to measure the viscosity and structural information of the CaO-SiO2-P2O5-FetO system at 1673 K. The experimental data have been compared with the calculated results using different viscosity models. It shows that the National Physical Laboratory (NPL) and Pal models fit the CaO-SiO2-P2O5-FeOt system better. With the P2O5 content increasing from 5% to 14%, the viscosity increases from 0.12 Pa s to 0.27 Pa s. With the FeO content increasing from 30% to 40%, the viscosity decreases from 0.21 Pa s to 0.12 Pa s. Increasing FeO content makes the complicated molten melts become simple, and increasing P2O5 content will complicate the molten melts. The linear relation between viscosity and structure parameter Q(Si + P) was obtained by regression analysis. The calculated viscosity by using the optimized NPL and Pal model are almost identical with the fitted values.

A novel method to smelt high-carbon ferrochromium by synergistic reduction with vanadium extraction tailings with high content chromium and chromite is proposed in this paper, which can efficiently recover chromium and iron from vanadium extraction tailings with high content chromium and produce high value-added products. The recoveries of chromium and iron reach 95.79% and 98.06%, respectively, and decrease with the increase of mass ratio. The smelting time has little influence on the recoveries of chromium and iron. The recoveries of chromium and iron decreased with the increase of reductant amount. The content of chromium and iron in the high-carbon ferrochromium is between 47.00% to 52.00%, and 35.00% to 60.00%, respectively. The contents of impurity elements in the high-carbon ferrochromium meet the expected requirements except nos. 7 and 8. The content of chromium reached 52.01% in the high-carbon ferrochromium. The optimum smelting conditions are mass ratio at 5:1, smelting 10 min, and C/O at 1.

The V-Cr-bearing reducing slag (VCBRS) is solid waste, which cannot be treated at present. This work proposes an effective approach to separately recover its major elements of V, Cr and Si and fully utilize the VCBRS with added-values. Flocculation desiliconization is used to extract Si from the acid solving liquid of VCBRS and Si is recovered as white carbon black with purity of 94.60% and recovery of 93.04%. After desiliconization, V in the solving liquid is selectively oxidized by H2O2 and extracted by microemulsion extraction, which is recovered as V2O5 whose purity is 99.60% with recovery at 96.32% from the stripping liquor of loaded microemulsion. Cr in the raffinate is recovered by alkaline precipitation as final product of Cr2O3 with purity of 98.83% and recovery of 92.68%. The principles are discussed in detail and the operation conditions are optimized systematically. The microemulsion and wastewater are both cyclically utilized, which eliminates the secondary wastes. This work efficiently recovers all valuable elements with increased values from the solid waste, which can not only solve the environmental pollution problem, but also realize the efficient recovery of valuable elements to achieve comprehensive utilization.

This paper investigated the non-isothermal crystallization kinetics of the spinel crystals in vanadium slags containing high CaO content. Experiments were performed in combination with theoretical calculation to address this issue, and statistical analyses based on the Crystal Size Distribution theory. The results indicate that low cooling rate and high CaO content benefit the growth of spinel crystals. The growth mechanism is revealed to be controlled by interface reactions and diffusion at the cooling rates of 5 K/min and 15 K/min, respectively. However, at higher temperatures (>1673 K), the growth of spinel crystals is controlled by nucleation. While the temperature is decreased to 1523 K at the cooling rate of 5 K/min, the mean diameter of spinel crystals could reach 36.44 μm. Experimental results combining with theoretical reveal that low cooling rate benefits spinels growth, especially for the interval of 1523 K–1200 K.

Aimed to utilize useful components and reduce the environmental impacts, the present study investigated the recycling of steel slag in converter steelmaking. A mathematical model based on the regular solution model was firstly developed to calculate the activities of calcium oxide and ferrous oxide and the substitution ratio of steel slag. The dephosphorization experiments were conducted in an induction furnace. In addition, theoretical analysis of the detailed heat expenditure items of dephosphorization agent was carried out. The heat enthalpy of unit mass slag was measured by differential scanning calorimetry. The results of dephosphorization experiments indicate that there is a sharp drop in phosphorus content in hot metal at the initial stage of dephosphorization. It was found that the optimal proportion of steel slag in dephosphorization agent is 20%. The heat enthalpy of unit mass slag No.1 and No.2 are 1164 kJ/kg and 1131 kJ/kg, respectively. The cooling capacity of steel slags are lower than the reference dephosphorization agent. One ton of reference dephosphorization agent made of 42% lime, 50% scale and 8% soda, could reduce the temperature of 80 ton of hot metals by up to 83.60 °C. The corresponding temperature drop by using No.1 and No.2 steel slags are 56.01 and 55.99 °C, respectively. For each increase of 5% substitution ratio with No.1 slag, the temperature drop of hot metal increases by 5.80 °C; for each increase of 5% substitution ratio with No.2 slag, the temperature drop of hot metal increases by 2.70 °C. The main factor that influences the temperature drop is the slag amount.

The phosphorus enrichment in solid phases during solidification of converter slag was studied by the modification with Al2O3. The mineral phase of the original and modified high phosphorus slags were analysed by SEM + EDS and XRD. The mechanism of Al2O3 modification was discussed based on thermodynamic modelling using the FactSage package. The results show that Ca3(PO4)2 and Ca2SiO4 precipitated first and formed the n2CaO·SiO2–3CaO·P2O5 (nC2S–C3P) solid solution. The content of Al2O3 has no significant impact on the initial precipitation amount of nC2S–C3P solid solution. High phosphorus solid solution (n′C2S–C3P) was generated by the constant reaction between nC2S–C3P (n′

In this paper, a series of nitriding experiments were carried out to investigate the phase evolution and element migration in the nitriding process. The results show that it undergoes a low temperature reducing stage firstly. High valent vanadium oxides are reduced to V2O3 between room temperature and 770 °C. In Ar atmosphere, V2O3 reacts with C to form VC in the temperature interval of 770 °C∼1080 °C. In N2 atmosphere, V2O3 reacts directly with N2 and C to form VN in the interval of 670 °C∼1050 °C. During 1050 °C∼1270 °C, part of the VN obtained in the previous reaction stage will react with C to form VC. High temperature is beneficial to the removal of impurity element sulfur. The volatilization of alkali metal elements in the pellet mainly occurs between 670 °C and 1270 °C. However, there are about 20% of sodium and potassium remain in the nitriding product. The volatile alkali metal vapor would react with other gases at the furnace cover to form a white sediment and deposits on the cover. The sediment mainly consists of Na2CO3, K2CO3, Na2SO4, K2SO4, KCl, etc.

Because of the interference from phosphorus, it is practically challenging to efficiently recover vanadium from vanadium slag with high phosphorus contents (VS-HPC). We propose to separate vanadium and phosphorus in aqueous medium via microemulsion extraction, which enables the recovery of vanadium from the leach solution obtained by conventional calcification roasting and acid leaching process of VS-HPC. The influences of various factors on the separation of vanadium and phosphorus have been investigated. Under the most suitable conditions, the extraction efficiency of vanadium can reach as high as 99.9% while that of phosphorus has been impressively lowered to 5.5%. After establishing the microemulsion-based separation method of vanadium and phosphorus, the vanadium element in VS-HPC was extracted to leach solution. The extraction and recovery of vanadium and phosphorus has further enabled, the production of V2O5 with a high purity of 99.7%; the high purity has made the products much more economically appealing than the commonly manufactured V2O5 with a purity of 98.0%. This work has provided new pathways of promoting sustainability in the non-ferrous metal resource utilization.

Present methods of vanadium extraction from vanadium slag suffer from serious environmental pollution due to the large production of solid waste and wastewater. This study proposes a cleaner method of magnesiation roasting–acid leaching, where magnesium oxide is considered to be a recyclable roasting additive. The maximum extraction efficiency achieved in case of vanadium is 95.56%, and the obtained vanadium pentoxide has a high purity of 99.07%. The magnesium in the leaching liquor is recovered as MgO with purity of 99.21%, and recovery rate of 90.13%, which is recycled as the roasting additive. Furthermore, manganese, ammonium sulfate, and water are recovered and recycled from the wastewater, while the ammonia produced during vanadate calcination is recycled. The resulted leaching residues are recyclable by burning in a blast furnace to recover their iron content for reuse. Herein, the recycling and reuse of all the wastewater and leaching residues result in zero discharge, significant cleanliness, and high resource utilization. This work has opened a new pathway of establishing significantly cleaner production process for environmental sustainability via design and incorporation of inner recycling of wastes into the process in which these wastes are produced.

In order to recover the tellurium and bismuth resources within the Dashuigou tellurium deposit in Sichuan province, China, the leaching of these metals from the raw ore in H2SO4 and FeCl3 media was investigated in this work. The effect of H2SO4 concentration, Fe3+ concentration, liquid/solid ratio, leaching time and leaching temperature was studied. It was found that 99.17% of Te and 92.82% of Bi were extracted into leaching solution under the optimum conditions: H2SO4 concentration of 150 g/L, Fe3+ concentration of 60 g/L, liquid/solid ratio of 6 ml/g, leaching time of 60 min and leaching temperature of 90 °C. Furthermore, the sulfur element in raw ore was reduced into elementary substance. There is no production of H2S, which is a positive indicator for environmental considerations.

Based on the classic kinetic theory of crystallization, we have developed a mathematical model to describe the crystallization behavior of crystals in complex vanadium–chromium slag systems. The results show that the crystallization rates of spinels, olivines and augites are dominated by the component with the highest melting point. The sequence of the crystallization ability of crystals in vanadium–chromium slag is as follows: FeCr2O4 > Mg2SiO4 > FeV2O4 > MgSiO3 > Fe2TiO4 > Mn2SiO4 > MnSiO3 > Fe2SiO4. The optimum temperature ranges for the crystallization of these crystals are 1497–1547 K, 1380–1430 K, 1301–1351 K, 1192–1242 K, 1098–1148 K, 1069–1119 K, 1038–1088 K and 985–1035 K, respectively. We also find that with the increase in Cr2O3/V2O3 and decrease in SiO2/FeO, the total crystallization rate of spinels increases remarkably, while the TiO2 content has little effect on the crystallization of spinels in vanadium–chromium slag.