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In this work, the sulfur-free emission route for the synthesis of Mo and Mo2C via carbothermal reduction of MoS2 was proposed. The internal MoS2-C mixture is wrapped by an external desulfurization layer composed of CaO and C. In the internal layer, MoS2 reacted with carbon black and generated Mo, Mo2C (or their mixture), as well as S2, CS2 and CS gas. Both experiments and thermodynamic calculations show that the main gaseous product should be CS2. The sulfur-containing gas produced can be completely captured by the desulfurization layer in the form of CaS. This strategy can avoid the emission of S-containing gas compared with the traditional route. In addition, after removing the unreacted desulfurizer and gently breaking the desulfurization product layer, the molybdenum-containing product can be collected. For the raw material with a MoS2:C molar ratio of 1:1, after reacting at 1600 °C for 4 hours, Mo with carbon and sulfur contents of 0.053 and 0.050 pct is acquired. In addition, Mo2C-dominant product can be obtained after reacting at 1600 °C for 4 hours at a MoS2:C molar ratio of 1:1.52, with the carbon and sulfur contents of 5.878 and 0.049 pct. The above shows that this strategy has the advantages of high-efficiency desulfurization and simple separation of desulfurization product, which is an environment-friendly method for the production of molybdenum additives.

The morphology evolution from monoclinic molybdenum trioxide (β-MoO3) to orthorhombic molybdenum trioxide (α-MoO3) and quantitative analyses of their mixtures were examined. It was found that the morphology (from spherical to elliptical shape) and color (from green to white) displayed obvious changes when β-MoO3converted to α-MoO3in ambient air at 773 K. The transformation from β-MoO3to α-MoO3resulted from a change of the internal crystalline structure. The mass percent of β-MoO3in MoO3mixtures showed an excellent linear relationship with the relative intensity ratio of the strongest peaks in X-ray diffraction patterns. This approach provides a simple and time-saving method to evaluate the amount of β-MoO3, which is a promising material in catalyst and electrochemical applications, in such mixtures. This finding may provide guidance for the analysis of catalytic performance of MoO3mixtures. In addition, it was found that β-MoO3can be easily decomposed into suboxides such as MoO2and Mo4O11in pure argon gas atmosphere. The possible decomposition mechanism of β-MoO3is discussed.

Stainless steel pickling sludge is the precipitate from the neutralization process of stainless steel pickling liquor. Until now, many methods about the harmless treatments of pickling sludge have been developed, and among them the most effective one is to produce Fe-Cr-Ni alloy by carbothermic reduction process. However, the carbon and sulfur (harmful elements for steel) contents of the produced Fe-Cr-Ni alloy are difficult to be controlled, especially for the high-CaSO4 sludge. The current paper proposed a new method to produce the low-carbon and low-sulfur Fe-Cr-Ni-Si alloy by using the high-CaSO4 stainless steel pickling sludge. Firstly, the sludge was pre-reduced by carbon at 1100 °C. Then, the pre-reduced sludge was mixed with silicon powder and reacted at 1550 °C for the deep reduction, separation, and desulfurization. By the current method, the Fe-Cr-Ni-Si alloy with a carbon content of 0.513 wt pct and a sulfur content of 0.003 wt pct was produced. Meanwhile, the Fe, Cr, and Ni contents in alloys were 59.600, 15.440, and 13.570 wt pct, with recovery rates of 97.99, 97.61, and 98.65 pct, respectively. Such an alloy can be used as the alloy additive for stainless steel production.

High-quality ferrovanadium nitride (FeV45N, FeV55N and Fe65N) was fabricated using the raw materials of Fe3O4, V2O5 and graphite via carbothermal reduction nitridation method. Compared with the traditional methods, it shortens the production process of ferrovanadium nitride by avoiding the preparation of ferrovanadium. The effects of C/O molar ratio and reaction temperature on phase transition, density, carbon, oxygen and nitrogen contents and microstructure were investigated. The appropriate C/O molar ratio is crucial to obtain the products with high nitrogen content. It is also found that a higher temperature is beneficial for the densification, and the density of the products obtained at 1550 °C is much higher than that at 1500 °C. Moreover, a higher temperature contributes to the increase in nitrogen content owing to the higher reaction kinetics. The carbothermal reduction nitridation method is proved to be a facile route to fabricate cost-effective ferrovanadium nitride and is possible to be applied for industrial production.

In this study, high-purity and ultrafine WC-6%Co composite crystallites was synthesized by a simple two-step process consisting of the precursor-formation of the mixture of blue tungsten oxide (WO2.9) and cobaltic oxide (Co2O3) and the following deep reduction and carburization with CH4-H2 mixed gases. The experimental results revealed that after the first carbothermic reduction stage at 1050 or 1150 °C, a mixture of W, WO2 and Co7W6 was obtained, which was further carburized to the WC and Co phases by CH4-H2 mixed gases at 900 °C. With the increase of C/WO2.9 molar ratio, the particle sizes of first-stage precursor and carbonized product were both decreased. The particle sizes of final products are mainly determined by C/WO2.9 ratio and reaction temperature at the first stage. When the C/WO2.9 ratio was in the range of 2.3–2.7, the high-purity WC-6%Co composite powder with the average particle sizes of 160–410 nm could be obtained.

The present study utilized W nanopowders (prepared by a two-stage reduction process consisting of steps of carbothermic pre-reduction and hydrogen deep reduction) to produce fine-grained 90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe alloys. The effects of sintering temperature [in a range of 1573 K to 1723 K (1300 °C to 1450 °C)] and time on the microstructure and mechanical properties of W-Ni-Fe alloys were studied in detail. The microstructures of the prepared alloys at 1573 K and 1673 K (1300 °C and 1400 °C) indicated that the grain sizes of W grains are 5 μm after sintering for > 60 minutes at 1723 K (1450 °C). The observation shows the as-sintered alloys with different holding times exhibit different fracture modes. With increasing holding time, the hardness of two alloys first increases and then decreases at the same sintering temperature. It is also concluded that the bending strength of alloys increases with the increase of sintering temperature. The maximum hardness of 381 and 393.6 HV was obtained after sintering at 1573 K (1300 °C) for 60 minutes for 90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe alloys, respectively, while the highest bending strength of 1381.4 and 1278.8 MPa could be achieved at 1673 K (1400 °C) for 120 minutes. The excellent mechanical properties of W-Ni-Fe alloys could be attributed to the grain refinement strengthening.

The mixed alkali effects of Li2O, Na2O, and K2O on viscosity of CaO-SiO2-Al2O3 melts are investigated by rotating cylinder method. It is found that the single addition of Li2O, Na2O, or K2O to CaO-SiO2-Al2O3 melt will reduce the viscosity of melt, regardless of the Al2O3 content, while the degree of reduction follows the sequence of Li2O > Na2O > K2O. For melts containing two alkali oxides, viscosity monotonically decreases when one alkali oxide is replaced by another at all temperature investigated in this paper, but no extrema of viscosity is found like the behavior of electrical conductivity. In addition, the extrema are not found in the slag containing three alkali oxides if changing their relative contents but keeping their total contents constant. Raman spectroscopy is used to illustrate the relationship between viscosity and structure of melt and it is found that degree of polymerization is the major factor affecting the viscosity of melt.

The method of calciothermic reduction of B4C was proposed for preparing CaB6. The phase transition and morphology evolution during the reaction were investigated in detail. The experimental results reveal that Ca first reacts with B4C to generate CaB2C2 and CaB6 at a low temperature and that the CaB2C2 subsequently reacts with Ca to produce CaB6 and CaC2 at a high temperature. After the products were leached to remove the byproduct CaC2, pure CaB6 was obtained. The grain size of the prepared CaB6 was 2–3 μm, whereas its particle size was 4–13 μm; it inherited the particle size of B4C. The residual C content of the product was decreased to 1.03wt% after the first reaction at 1173 K for 4 h and the second reaction at 1623 K for 4 h.

We propose a process to produce ultrafine W-10 wt pct Cu composite powders by reducing the mixtures of copper tungstate (CuWO4) and tungsten trioxide (WO3) (from the calcination of a mixture of ammonium paratungstate and copper nitrate trihydrate) with carbon black and hydrogen. First, ultrafine pre-reduced tungsten-copper (W-Cu) powders containing a small amount of WO2 were produced by reducing mixtures of CuWO4 and WO3 with insufficient carbon black; then the obtained products were further reduced by hydrogen to remove the residual oxygen. This method provides a simple and low-cost route to prepare ultrafine W-10 wt pct Cu composite powders. The composite powders were sintered at different temperatures [1323 K (1050 °C), 1373 K (1100 °C), 1423 K (1150 °C), 1473 K (1200 °C), and 1523 K (1250 °C)] for 3 hours. A maximum densification of the obtained compact was achieved at a sintering temperature of 1523 K (1250 °C), with a relative density, Vickers hardness and thermal conductivity of the W-10 wt pct Cu composites of 97.8 pct, 365 HV and 165 W/m K, respectively.

Vanadium diboride (VB2) powders with low oxygen content are prepared via a molten-salt-assisted borothermal reduction reaction at 1123 K to 1273 K (850 °C to 1000 °C) using V2O3 and boron powders as the raw materials. The effects of the amount of molten salt and reaction temperature on the phase transition and morphology of the final products are investigated. The results reveal that the addition of molten salt is beneficial for decreasing both the synthesis temperature and particle size of the final products. When the mass ratio of NaCl to reactants is 0.75:1, the VB2 powders prepared at 1173 K (900 °C) have a particle size lower than 100 nm. Too little or too high molten salt addition has a negative impact on the preparation of the VB2 powders. Furthermore, the reaction temperature has an important impact on the morphology and purity of the VB2 particles. An appropriate reaction temperature (1173 K (900 °C)) is beneficial for controlling the size of the VB2 particles in the order of nanoscale and improving the quality of the VB2 powders.

In the current study, ultrafine and high-purity tungsten carbide (WC) powders are successfully prepared by a two-step process: carbothermic reduction of WO3 followed by carbonization reaction. The effects of the C/WO3 molar ratio, reaction temperature and reaction time on the phase transition and morphology evolution of the products are investigated. During the carbothermic reduction process, all the oxygen in yellow tungsten trioxide (WO3) is removed by carbon to generate a mixture of W, W2C and WC at 1100 °C; and then the as-prepared powder is mixed with an appropriate content of carbon black and carbonized at 1200 °C. The carbon content in the finally obtained WC powders is almost equal to the theoretical value. Furthermore, it is found that a high C/WO3 molar ratio at the first stage is beneficial for decreasing the particle size of the WC powders. When the C/WO3 molar ratio is 3.5, the single phase WC with a particle size of about 200 nm can be obtained. Therefore, this carbothermic reduction–carburization process may provide a simple, low-cost, and high efficiency route to prepare the WC powders in a large-scale.

Particle size dependence of CO2 absorption rate of powdered Ba2Fe2O5 with three kinds of particle size was studied by XRD, SEM, particle size distribution measurement and thermogravimetry. From the particle size distribution measurement, average particle sizes of the powdered Ba2Fe2O5 samples were estimated about 52.5 μm, 77.5 μm and 100.0 μm, respectively. Results show that the reaction of CO2 with Ba2Fe2O5 was controlled by the diffusion step in the product layer, and the kinetics process could be described by the RPP model (Real Physical Picture). Moreover, Ba2Fe2O5 exhibits a good recycling performance though the adsorption capacity is reduced slightly during the cycle processes, and the pathway of the CO2 adsorption–desorption on Ba2Fe2O5 has also been obtained, which suggested that Ba2Fe2O5 is a promising CO2 absorbent material.

The development of a highly efficient and low-cost production process is instrumental for the wide application of vanadium nitride (VN). The strong affinity of vanadium with carbon and oxygen resulted in the significant difficulty to produce VN with a high purity. In this paper, a novel production route was proposed that involves the magnesiothermic reduction and nitration of vanadium (III) oxide (V2O3) in nitrogen atmosphere with the assistance of magnesium chloride (MgCl2) in the temperature range of 948 K to 1073 K (675 °C to 800 °C). Compared with the traditional methods, there was no contamination of carbon. Meanwhile, oxygen content can be controlled to a low level. Furthermore, VN could be prepared at low temperatures within a short time, which was beneficial for decreasing the particle size of VN. The phase transition and morphological evolution of samples were analyzed by X-ray diffraction and Field-Emission Scanning Electron Microscopy, respectively. The experimental results showed that high temperature assisted in decreasing the residual oxygen content in VN but can decrease the specific surface area. Oxygen content of the obtained VN powder after reacting at 1073 K (800 °C) for 3 hours was 1.36 wt pct.

A method of preparing Mo2C via vacuum carbothermic reduction of MoS2 in the temperature range of 1350–1550°C was proposed. The effects of MoS2-to-C molar ratio (α, α = 1:1, 1:1.5, and 1:2.5) and reaction temperature (1350 to 1550°C) on the reaction were studied in detail. The phase transition, morphological evolution, and residual sulfur content of the products were analyzed by X-ray diffraction, field-emission scanning electron microscopy, and carbon–sulfur analysis, respectively. The results showed that the complete decomposition of MoS2 under vacuum is difficult, whereas activated carbon can react with MoS2 under vacuum to generate Mo2C. Meanwhile, higher temperatures and the addition of more carbon accelerated the rate of carbothermic reduction reaction and further decreased the residual sulfur content. From the experimental results, the optimum molar ratio α was concluded to be 1:1.5.

In this work, a two-stage process was developed to recover the valuable elements from chromium-containing electroplating sludge (CES). The low sulfur/carbon Fe-Si-Cr alloy containing 31.61%Fe, 31.78%Cr, 36.59%Si, 0.01%C and 0.01%S was produced, and the recovery extent of Cr reached 98.62%. The CES was pre-desulfurized at 1000–1200 ℃, and reaction between components CaSO4 and Fe2O3 in the CES to produce CaFe4O7 was the main desulfurization mechanism. The desulfurized CES was then reduced by silicon at 1600 ℃ to prepare the Fe-Si-Cr alloy, and the SiO2 generated from the silicothermic reduction helps the vitrification of the slag. The presence of silicon in alloys and the CaO in the slag are the key factors for the low content of sulfur in alloy. Adding CaO also helped to decrease the viscosity of slag, and thus reduced the metal loss by enhancing the slag-metal separation efficiency.

In order to evaluate the effect of precursors and synthesis strategies on catalytic ability of Mo2C in the hydrogen evolution reaction (HER), four kinds of Mo2C were synthesized using two kinds of MoO3 by two strategies. Compared with the one-step direct carbonization strategy, Mo2C with a large special surface area and a better performance could be synthesized by the two-step strategy composed of a nitridation reaction and a carbonization reaction. Additionally, the as-prepared porous Mo2C nanobelts (NBs) exhibit good electrocatalytic performance with a small overpotential of 165 mV (0.5 M H2SO4) and 124 mV (1 M KOH) at 10 mA cm−2, as well as a Tafel slope of 58 mV dec−1 (0.5 M H2SO4) and 59 mV dec−1 (1 M KOH). The excellent catalytic activity is ascribed to the nano crystallites and porous structure. What’s more, the belt structure also facilitates the charge transport in the materials during the electrocatalytic HER process. Therefore, the two-step strategy provides a new insight into the structural design with superior performance for electrocatalytic HER.

The electrical conductivity of Fe x O-CaO-SiO2-Al2O3 slags was measured by a four terminal method. The results show that the temperature dependences of total, electronic and ionic conductivity for different compositions obey the Arrhenius law and all of them increase as increasing the temperature. For all the studied slags, as increasing CO/CO2 ratio which is used to controlled the oxygen potential, both the total electrical conductivity and electronic conductivity increase, but the ionic conductivity decreases. It was also found that the electronic transference number exhibits a strong correlation with oxygen potential, but is independent of temperature. Under the condition of constant FexO content, the higher the basicity of slags is, the higher the total electrical conductivity and ionic/electronic conductivity will be, which is resulted from the increase of free oxygen ion.

In this study, 93 wt.% tungsten heavy alloys reinforced with highly uniform and dispersed ZrO2 particles were successfully manufactured by powder metallurgy method. In order to fabricate fine-grained tungsten heavy alloys with outstanding performances, ultrafine 93W-4.9Ni-2.1Fe composite powder fabricated using a two-step reduction approach was selected as raw material. Microstructure and mechanical properties were experimentally examined to investigate the influence of ZrB2 addition. Meanwhile, transmission electron microscope and energy spectral analysis identified that ZrO2 particles were generated through the reaction between ZrB2 and oxygen from the grain boundaries. The ultimate tensile strength, elongation, and hardness of 93W-0.75ZrB2 alloys could reach to 963 ± 16 MPa, 18.4 ± 1.3% and 387.6 ± 4.4 HV, respectively, benefitted from the combination of fine-grained strengthening and oxide dispersion strengthening mechanisms. The W grains without observable texture were homogeneously distributed in the γ matrix phase based on electron back-scattered diffraction analysis. Moreover, it was determined that the main fracture types of 93W-ZrB2 alloys were W grain cleavage failure and ductile matrix rupture, closely related to the ZrB2 content in alloys. The current work provided a possible method for purifying the boundaries and enhancing the strength and elongation of W-Ni-Fe alloys simultaneously.

In this paper, a novel process about the silicothermic reduction of molybdenum disulfide was proposed to prepare molybdenum silicides. This new method has a short process, which is beneficial for energy saving, environmental protection and cost reduction relative to the traditional methods by using pure molybdenum and silicon as the raw materials. It was found that the phase compositions and microstructures of products were greatly influenced by the molar ratio of Si to MoS 2 and temperature. From the experimental results, it was concluded that MoSi 2 , Mo 5 Si 3 and Mo 3 Si can be prepared when the temperature was above 1100 °C, 1300 °C and 1500 °C, and the Si/MoS 2 molar ratio was 4, 2.6 and 7/3, respectively. When the Si/MoS 2 molar ratio was less than 4 and the temperature was below 1100 °C, only one Mo-Si compound (MoSi 2 ) was generated; while above 1200 °C, the excessive MoS 2 could react with MoSi 2 to generate Mo 5 Si 3 , but Mo 5 Si 3 can't react with excessive MoS 2 below 1300 °C; until above 1400 °C, Mo 5 Si 3 and MoS 2 can react to generate Mo 3 Si. However, even at 1600 °C, excessive MoS 2 couldn't react with Mo 3 Si but can be decomposed. Besides molybdenum silicides, other products SiS or SiS 2 can also be generated. SiS could escape from sample at 1100 °C in the form of gas while SiS 2 couldn't. Both the increases of temperature and molar ratio of Si to MoSi 2 were beneficial for the decrease of the residual sulfur content in the final products. From the experimental results, it was found that as increasing the temperature or the molar ratio of Si to MoS 2 from 7/3 to 4, the grain size of products increased and the sintering phenomenon among grains was more and more obvious.

The influence of SiC particle on viscosity of CaO–MgO–Al2O3–SiO2 melts was investigated by the rotating-cylinder method. It was found that temperature dependence of viscosity could be descr...

The electrical conductivity of molten slag has many important and practical effects in modeling and operating the electric smelting furnace. In the present study, the electrical conductivities (total and electronic/ionic properties) of MnO-CaO-SiO2 slags were measured by a four-electrode method at different oxygen potentials and temperatures. Experimental results show that the effects of temperature on the total, electronic, and ionic conductivities obey the Arrhenius law, and all conductivities increase when increasing the temperature. The stepped potential chronoamperometry method was used to measure the electronic transference number, which is affected strongly by oxygen potential but is unaffected by temperature. The total electrical, electronic, and ionic conductivities present similar increasing trends when increasing the CO/CO2 ratio, which resulted from increasing Mn2+.

The knowledge of redox equilibria of iron in multicomponent molten slags is of significant importance to understand the viscosity, electrical conductivity and structure of iron-containing slags. However, the available data of molar ratio of ferric ion to ferrous ion are limited due to the difficulty of experiment and heavy workload. In this study, a model was established to estimate the $${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ (normally, most of ferric ions exist in the form of complex anions such as $${\rm{FeO}}_2^ - $$) ratio in CaO–MgO–Al2O3–SiO2–“FeOt” slags, which can give good estimation results compared to the experimental measured values. From the model, by increasing oxygen partial pressure or decreasing temperature, the $${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ ratio will increase. Different components have different influences on $${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ ratio: CaO and MgO are beneficial for the increase of this ratio, but Al2O3 and SiO2 have reverse effects.

Industrial grade MoO2 powders have a plenty of advantages relative to MoO3 in the direct alloying steelmaking processes. In this work, the reduction of industrial grade MoO3 powder with CO gas or the mixed gases of CO and CO2 has been investigated in detail in order to prepare industrial grade MoO2 powder. It is found that reaction temperature has a significant effect on the product composition. Using pure CO as the reducing gas, for temperatures below 868 K (595 °C), the main product is MoO2 with some whisker carbon; for temperatures above 868 K (595 °C) the main reaction products are MoC and amorphous carbon; as the reaction temperature further increased, the final reaction product is Mo2C. In addition, Mo4O11 is always formed as an intermediate product during the reaction processes both at lower and higher temperatures, which is similar to that observed on reduction of MoO3 by H2. It is found that adding CO2 to the reducing gases eliminated carbon formation but still allows the formation of MoO2 during the reaction process. This method may be applied to produce industrial grade MoO2.

A commercial route has been developed to synthesize submicrometer titanium nitride from titanium dioxide/phenolic resin composite. The phenolic resin served as the carbon source and the titanium dioxide served as titanium source to produce titanium nitride in flowing ultrahigh purity N2 atmosphere at 1373–1773 K. Titania was embedded in a continuous phenolic resin dispersant. X-ray diffraction and field emission scanning electron microscope were employed to characterize the phase composition, microstructure and reaction mechanism. It was found that the reaction sequence was TiO2 → Ti4O7 → Ti3O5 → TiN and the whole formation process was consisted of chemical synthesis reaction process firstly and the following recrystalline-physical process. The optimal conditions to prepare titanium nitride powders were determined: the molar ratio of titanium dioxide to phenolic resin is 1:0.5; thermostatic temperature is 1773 K, and thermostatic time is 2 h. The stepped structure on the surface of product formed due to recrystallization. The particle size of the obtained titanium nitride powders is about 0.5 μm.

The medium W content W–Ni–Fe alloys have a combination of high strength and great ductility, revealing a promising future for widespread engineering applications. In order to fabricate medium W content W–Ni–Fe alloys with outstanding performances, W nano-powders prepared by a two-stage reduction method was employed as raw material. Meanwhile, the finely dispersed Al2O3 particles have effective roles in restraining the growth of W grain. Electron back-scattered diffraction analysis identified that fine W grains were uniformly distributed in the γ matrix phase without any observable texture. Benefitting from the combination of fine-grain strengthening, oxide dispersion strengthening and precipitation strengthening, a highest tensile strength of 816 ± 11 MPa and a greatest elongation of 29.7 ± 1.2% are obtained for the sintered alloys of 75 W–1Al2O3 and 50 W, respectively. It is also concluded that the main fracture modes of the currently manufactured alloys are ductile matrix rupture and W-matrix interface separation.

The effects of Li2O/(Li2O + Na2O) ratio and temperature on structure, crystallization, microstructure and mechanical properties of SiO2-CaO-Al2O3-TiO2-9 mol% R2O glass ceramics were investigated by melting-sintering method. It was concluded that as substituting Li2O for Na2O, the degree of polymerization of glass first increased and then decreased by Raman spectra analysis. The activation energy of crystallization was in the range of 165–193 kJ/mol, and the crystallization behavior was dominated by bulk crystallization. When the glass samples were heat treated at 750 ℃, only glass containing 9 mol% Li2O crystallized, and the crystalline phases were β-quartz solid solution and wollastonite phases; while when heat treatment temperature increased to 800 ℃ or 850 ℃, the main crystal phase changed from granular wollastonite to fine-grained β-spodumene phase as replacing Na2O by Li2O. In addition, both the flexural strength and Vickers hardness first increased and then decreased with the increase of Li2O/(Li2O + Na2O) ratio.

In this study, a thermodynamic analysis of the reaction between MoS 2 and Si was performed, which indicated that when the molar ratio of MoS 2 to Si is 1:4, the final products were composed of SiS and MoSi 2 , without other solid phases, in the temperatures range of 0 °C–1700 °C. The reaction between MoS 2 and Si powders with a MoS 2 /Si molar ratio of 1:4 was investigated in the range of 800 °C–1600 °C. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the phase composition and microstructure of the products, respectively. The content of sulfur in MoSi 2 product was measured using an infrared carbon-sulfur analyzer. It was found that pure MoSi 2 can be successfully synthesized in the temperature range of 1100 °C–1600 °C after reacting for 2 h with very little sulfur residual. Meanwhile, gaseous SiS was also generated and escaped from the MoSi 2 . It was also found that the reaction rate between MoS 2 and Si was very slow at 800 °C and 900 °C. The microstructural analyses indicated that grain size of the MoSi 2 product increased with increasing temperature.

To investigate the flow of primary slag bearing TiO2 in the cohesive zone of blast furnaces, experiments were carried out based on the laboratory-scale packed bed systems. It is concluded that the initial temperature of slag dripping increases with decreasing FeO content and increasing TiO2 content. The slag holdup decreases when the FeO content is in the range of 5wt%–10wt%, whereas it increases when the FeO content exceeds 10wt%. Meanwhile, the slag holdup decreases when the TiO2 content increases from 5wt% to 10wt% but increases when the TiO2 content exceeds 10wt%. Moreover, slag/coke interface analysis shows that the reaction between FeO and TiO2 occurs between the slag and the coke. The slag/coke interface is divided into three layers: slag layer, iron-rich layer, and coke layer. TiO2 in the slag is reduced by carbon, and the generated Ti diffuses into iron.