Oxide Silicate Research Articles

Evaluation of red sludge use efficiency for water purification from sulphates

In this work the reagent purification of aqueous solutions from sulfates with the use of red sludge of the Nikolaev alumina plant processes were investigated. This sludge, according to chemical analysis, contains a sufficiently large amount of alumina (up to 18 %) and calcium oxide (up to 10 %) and along with calcium silicate and iron oxides contains sodium and calcium aluminates. The ability of sodium aluminate to be deposited from a solution of sulfates in the form of calcium sulfoaluminates was used in the work to purify water from sulfate anions. The process takes place when treating the solution with sludge and lime suspension. It is shown that when red sludge is applied in the amount of 1–50 g/dm3 during magnesium sulfate solutions liming, water is purified from sulfate anions. The degree of water purification reaches 50–70 %. It was found that the efficiency of sulfate extraction is significantly dependent on the consumption of lime and increases slightly with increasing sludge consumption over 1 g/dm3. The dependence of the efficiency of sulfate extraction from water on their initial concentration is determined. It was found that at the initial concentration of sulfates up to 1000 mg/dm3 at the expense of lime 3–12 mg-eq/dm3 the residual concentration of sulfates decreases to 236–460 mg/dm3, and at the concentration of sulfate anions about 2000 mg/dm3 their concentration decreases to 550–830 mg/dm3 at a lime consumption of 30 mg-eq/dm3 regardless of the sludge consumption. The degree of extraction of sulfates from solutions reaches 40–73 %.

Systematic characterization of THz dielectric properties of multi-component glasses using the unified oscillator model

A terahertz (THz) dielectric property characterization method based on a unified single oscillator model has been developed and applied to a variety of multi-component silicate oxide glasses. The experimental values of dielectric constant determined by THz time-domain spectroscopy (TDS) in the sub-THz region have been confirmed to agree well with the values calculated by the single oscillator model which incorporates the local field effects and the material’s ionicity. This has provided a unified formulation that enables systematic determination of the key physical parameters solely from the high-frequency (optical) and low-frequency (sub-THz) dielectric constants and characteristic resonance frequency in the (sub-)THz region. The low-frequency dielectric constant has been demonstrated to be fully determined by a single parameter of the microscopic total susceptibility. Also, the polarization ionicity, which is defined by the ionic fraction in the microscopic total susceptibility, has been found to be a good indicator to represent the ionic nature of the material. Through this analysis, an increasing trend of the effective ionic charge has been found in high-dielectric constant glasses such as oxyfluorosilicate glasses, and the physical mechanism of their dielectric constant enhancement has been discussed. The present method is expected to be applied to design and characterize dielectric properties of a wide range of multi-component glasses and other isotropic, insulating materials.

A dense ZrB2-SiC-Si/SiC-Si coating to protect carbon/carbon composites against oxidation at 1773 K and 1973 K

A dense double layer ZrB2-SiC-Si/SiC-Si coating with high content of ZrB2 was designed and fabricated by dipping-carbonization joint gaseous silicon infiltration. This coating can protect C/C substrate from oxidation in air at 1773 K for 500 h with a weight gain of 1.14 %. Such good oxidation protective performance was ascribed to the dense compound silicate oxide layer accompanied by ZrSiO4/ZrO2 pinning phases and compressive stress field around ZrB2 particles during oxidation. Besides, introducing abundant ZrB2 phase could inhibit the evaporation of silicate glass at 1973 K, which could protect C/C composites for 78 h with a weight loss of 1.16 %.

Molecular structures in the inorganic-metal interactions for optimizing electrochemical performance

Plasma-assisted electrochemical reactions (PAE) on the metal surface of light metals were studied via low temperature-interfacial plasma electrolysis (LT-PE) in the presence of nitrogen-containing organic compounds. The surface treatment was achieved in a silicate-based electrolyte, having Melamine (MEL), adenine (AD), and N.N.N′.N′-tetramethylenediamine (TEMD), which might act as an oxygen scavenger and as metal ions-acceptors during the plasma-assisted electrochemical reaction. The existence of MEL and TEMD working as the donor of nitrogen and carbon would boost the fabrication of magnesium silicate and magnesium oxide in the inorganic layer, resulting in outstanding compactness of the inorganic film to that when AD, having several tautomers, was acted as acceptor-type ions since the formation of stable organic complexes was preferred in the electrolyte solution with AD. The porosity of the inorganic layer formed by AD was higher than MEL and TEMD due to the adenine hydrogen bonding between AD molecules. The finding in this work indicates that the corrosion protective action was remarkably improved in the order of TEMD, MEL, and AD, which was discussed on the basis of potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) interpretations.

Communication—Magnetic Properties of Fe/Na2SiO3/Fe3O4 Soft Magnetic Composite by Two-Stage Ball Milling

Iron-based soft magnetic composites (SMCs) were prepared by two-step ball milling with sodium silicate and ferroferric oxide. The presence of the precoated silicate layer has increased the resistivity of the powder surface, which also improved the agglomeration of ferroferric oxide. The addition of magnetic ferroferric oxide improves the dilution effect. Combining the advantages of both sodium silicate and ferroferric oxide, the prepared soft magnetic composite material has excellent performance. After annealing at 400 °C, the core loss is 214.5 W Kg−1 (1 T, 1000 Hz), and the saturation magnetic induction is 1.33 T.

Relative Abundance and Compositional Variation of Silicates, Oxides and Phosphates in the W-Sn-Rich Lodes of the Panasqueira Mine (Portugal): Implications for the Ore-Forming Process

Panasqueira is a world-class W-Sn-Cu lode-type deposit located in Portugal. It consists of a dense swarm of subhorizontal quartz lodes criss-crossed by several ENE–WSW and N–S fault zones, bordering Late Variscan granite and hosted in Late Ediacaran—Early Cambrian metasediments. The relative abundance and compositional variation (assessed with EPMA) of the main silicates, oxides and phosphates forming the quartz lodes and their margins were examined, aiming to explore: (i) mineral and geochemical zonation at the mine scale; and (ii) some conclusions on the chemical nature of prevalent fluid inflows and T-conditions of mineral deposition. Quartz lodes nearby or far from the known greisen-granite cupola display significant differences, reflecting multiple fluid influxes of somewhat distinct composition related to various opening and closing events extending for several My, ranging from an early “oxide–silicate stage” (OSS) to a “main sulfide stage” (MSS), and further on to a post-ore carbonate stage (POCS); however, a rejuvenation event occurred after MSS. The onset of OSS was placed at ca. 299 ± 5 Ma and the rejuvenation event at ca. 292 Ma. The OSS was confined to ≈500 ≤ T ≤ 320 °C, following rutile and tourmaline growth under ≈640 ≤ T ≤ 540 °C (depending on aSiO2). The rejuvenation event (≈440–450 °C) preceded a late chlorite growth (≈250–270 °C) and the progression towards POCS.

Characterization of heat resistant hydraulic sealer for warm vertical obturation

ObjectiveWarm vertical compaction of gutta-percha is a technique that is used by most specialists for root canal obturation. The sealers currently available exhibit irriversible chemical changes when heated. New biologically active sealers that do not sustain irreversible changes when heated are an attractive alternative to be used with warm vertical compaction obturation technique. The aim of this study was to measure the heat generated by warm vertical compactors inside the root canal, characterize a newly developed root canal sealer at different temperatures and verify its suitability at the actual temperature window used clinically. MethodsThe typical temperatures generated by two heat carriers in a root canal were assessed by thermocouples. Two premixed root canal sealers TotalFill BC and HiFlow BC (FKG, Switzerland) were allowed to set and they were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD) immediately after setting and by XRD after 28 days in physiological solution. The ion leaching in solution was assessed by inductively coupled plasma (ICP). The organic component was extracted in acetone and assessed by Fourier transform infrared spectroscopy (FT-IR) for both the unset sealer and sealer subjected to different temperatures. The heat profiles of both sealers were investigated by FT-IR and thermographic analysis. ResultsNone of the devices tested achieved the temperatures set on the dial. The highest temperatures were coronal followed by apical for both devices. The sealers were identical except for the vehicle. The inorganic components included tricalcium silicate, dicalcium silicate and zirconium oxide. No calcium hydroxide was produced by any of the sealers after immersion in physiological solution but calcium was released in solution. The chemistry of both sealers was modified when heated but both recovered when cooled. SignificanceThe heat carriers were unreliable and the heat generated inside the canal was not the same as the temperature set on the dial. Since both sealers had identical chemistry save for minimal modifications to the organic component and were both resistant to heat, TotalFill BC sealer is recommended for use with warm vertical compaction technique as it is cheaper and as effective as the HiFlow.

Synthesis of volcanic ash-based geopolymer with calcium oxide (CaO) addition for building material application

Volcanic ash is a natural pozzolanic material with high mol ratio SiO2/Al2O3 but low in CaO. This research aims to study the volcanic ash geopolymer characteristics related to CaO addition. Geopolymers are prepared by mixing volcanic ash, alkali activator solution, sodium silicate, and calcium oxide. Calcium oxide added varies 5–135 g with each interval is 5 g in Solid/Liquid (S/L=1.83) ratio. Geopolymer characteristics investigated include setting time, compressive strength, resistance to sulfuric acid and mineral phase. The results showed that the more CaO was added, the shorter the setting time and the greater the compressive strength until it reached optimum. The amount of optimum CaO that added is 30 g, with the setting time 2.61 hours and the compressive strength 36.26 MP better than the volcanic ash geopolymer without CaO as 103 hours in setting time and 20.34 in compressive strength. Volcanic ash-based geopolymer at the optimum CaO addition proved to be better than cement mortar, which has a shorter setting time, greater compressive strength and greater resistance to sulfuric acid. Mineral phase analysis by XRD shows that the optimum geopolymer containing an amorphous phase with a major mineral is quartz and sodalite.

Climatic Variabilities Control the Solute Dynamics of Monsoon Karstic River: Approaches from C-Q Relationship, Isotopes, and Model Analysis in the Liujiang River

The dynamics of riverine solutes’ contents and sources reflect geological, ecological, and climatic information of the draining basin. This study investigated the influence of climatic variability on solute dynamics by the high-frequency hydrogeochemical monitory in the Liujiang River draining karst terrain of Guangxi Province, SW (Southwestern) China. In the study river, the content-discharge (C-Q) patterns of riverine solutes indicate that the majority of riverine solutes show similar dilution and near chemostatic behaviors responding to increasing discharge, especially geogenic solutes (such as weathering products from carbonate, silicate, and sulfide oxidation), whereas exogenous solutes (such as atmospheric input to riverine sulfate) and biological solutes (such as soil CO2) show higher contents with increasing discharge. Besides, the biological carbon is the main driver of the chemostatic behaviors of total dissolved inorganic carbon (DIC). The forward model results show that carbonate weathering dominates the water chemistry, and the weathering rates are intensified during high flow period due to additional inputs of weathering agents, i.e., the biologic carbonic acid from dissolution of soil CO2, indicated by δ13CDIC. In addition, there exists the strong capacity of CO2 consumption that is heavily dependent on climatic variables such as precipitation and air temperature in this study river. Our study highlights the impact of climatic variability on solutes dynamics and chemical weathering and thus must be better addressed in C models under future climate change scenarios.

Indium distribution in sphalerite from sulfide–oxide–silicate skarn assemblages: a case study of the Dulong Zn–Sn–In deposit, Southwest China

Economic interest in indium (In) and other critical metals has accelerated efforts to understand how such elements occur in nature and the controls on their mineralogy. In this contribution, the distribution of In and other trace elements in the Dulong Zn–Sn–In deposit, China, is described, using a holistic approach which targets not only sulfides but also the potential for In and Sn within co-existing oxides and skarn silicates. Sphalerite is the most significant In carrier. Four distinct types of sphalerite are identified, which differ with respect to ore texture and the concentration of In (0.74–4572 ppm). Subordinate amounts of In also occur within chalcopyrite and within andradite garnet, an abundant mineral in the skarn at Dulong and possibly accounting for a significant proportion of total In. Tin is not especially concentrated in either sphalerite or chalcopyrite, occurring instead as cassiterite but with measurable concentrations also in magnetite and skarn silicates. The study confirms that the dominant substitution for In in sphalerite is 2Zn2+ ↔ Cu+ + In3+ but that Ag and Sn may also play a subordinate role in some sphalerite sub-types via the substitution: 3Zn2+ ↔ Ag+ + Sn2+ + In3+. The study highlights that concentrations of In in sphalerite are likely to be heterogeneous at scales from single mineral grains to that of the deposit. The observed partitioning of both In and Sn into skarn silicates, and to a lesser extent, oxides, is a critical factor that may significantly compromise estimations of by-product elements that would be economically recoverable during exploitation of sulfide ores.

High refractive index properties of oxyfluorosilicate glasses and a unified dielectric model of silicate oxide glasses in the sub-terahertz frequency region

Dielectric properties of oxyfluorosilicate (OFS) glasses have been characterized using Terahertz (THz)-time domain spectroscopy in the sub-THz region as well as optical reflection measurement. OFS glass containing 20 mol% of Nb2O5, which is termed ZNbKLSNd glass, has the highest refractive index of 3.70 in the sub-THz region. The THz and optical refractive indices of various silicate oxide glasses, including OFS glasses, have been confirmed to be correlated by a unified relationship utilizing a parameter defined by the ratio of ionic to electronic polarizability. Additionally, the frequency dependence of the THz dielectric constant has been interpreted by a single oscillator model for all silicate oxide glasses including OFS glasses. On the basis of the present unified dielectric model, the very high refractive index of ZNbKLSNd glass has been attributed to the lowering of oscillator resonance wavelength originated from the incorporation of Nb2O5intermediate network former.

Running thermoregulation effects using bioceramics versus polyester fibres socks

The feet, covered by socks and shoes during running, undergo an increase of temperature. The aim of this study was to reduce heat generation in the feet of athletes during running by wearing novel thermoregulatory socks impregnated with bioceramic materials. Thirty male athletes ran a half-marathon (21.0975 km) wearing polyester based with bioceramic fibres (zirconium silicate and titanium oxide) and control socks (polyester). The average temperatures were measured with a thermographic camera (FLIR e60bx) before and after the run. Nine regions of interests were evaluated in the plantar surface and eight in the dorsum. Before running, the plantar region with the highest temperature was the inner midfoot (plantar arch) with 30.3 ± 2.1°C on the control sock and 30.2 ± 2.1°C on the bioceramic one. After running, smaller temperatures were found at the plantar surface of five regions of interests: heel, inner midfoot, first and fifth metatarsal heads and first toe and all the dorsal regions of the bioceramic socks. The amount of temperature reduction from the bioceramic sock was between –1.1 and –1.3°C in heel, inner midfoot, first MTH and first toe (plantar) and 1.3°C at the dorsum of first and fifth toes. Polyester-based socks with bioceramic fibre materials, due to far-infrared radiation, promote cooler temperatures on the sock surface after running. This effect is more effective in heel, the inner midfoot and the first MTH and could help improve the behaviour of the sock to make it denser in bioceramics and preventing running lesions, like blisters.

Density of amorphous GeO2 to 133 GPa with possible pyritelike structure and stiffness at high pressure

Germanium oxide is a prototype network-forming oxide with pressure-induced structural changes similar to those found in crystals and amorphous silicate oxides at high pressure. Studying density and coordination changes in amorphous $\mathrm{Ge}{\mathrm{O}}_{2}$ allows for insight into structural changes in silicate oxides at very high pressure, with implications for the properties of planetary magmas. Here, we report the density of germanium oxide glass up to 133 GPa using the x-ray absorption technique, with very good agreement with previous experimental data at pressure below 40 GPa and recent calculation up to 140 GPa. Our data highlight four distinct compressibility domains, corresponding to changes of the local structure of $\mathrm{Ge}{\mathrm{O}}_{2}$. Above 80 GPa, our density data show a compressibility and bulk modulus similar to the counterpart crystal phase, and we propose that a compact distorted sixfold coordination, similar to the structural motif of the pyritelike crystalline $\mathrm{Ge}{\mathrm{O}}_{2}$ polymorph, is likely to be stable in that pressure range. Our density data point to a smooth continuous evolution of the average coordination for pressure above 20 GPa with persistent sixfold coordination, without sharp density or density slope discontinuities. These observations are in very good agreement with theoretical calculations and spectroscopic measurements, and our results indicate that glasses and melts may behave similarly to their high-pressure solid counterparts with comparable densities, compressibility, and possibly average coordination.

Thermometry of Nickel Bearing Chlorites from the Kolskii Massif (Northern Urals)

The chemical composition of chlorites from the rocks that are conventionally classified as the residual weathering mantle of the Kolskii ophiolite massif was studied. The chlorites exhibit high Mg/ (Mg + Fe) atomic ratio values (Mg#) of 0.78–0.96 and elevated Si content (2.95–3.74 apfu), but are relatively poor in Al (1.28–2.66 apfu). In terms of octahedral occupancy (RVI is 5.52–5.98 and [R3+]VI is 0.87–2.04 apfu), they are classified as the trioctahedral subgroup. The NiO content in the chlorites varies from 0.2 to 21 wt %; in addition, the tabular low-Ni and high-Ni chlorite grains are often tightly intergrown. There is a pronounced negative correlation between NiO and MgO content. The crystallization temperature estimated using chlorite geothermometers varies widely. The crystallization temperature interval is 125–300°C or higher with a statistical maximum in the region of 175–300°C for the low-Ni chlorites and 50–250°С with a statistical maximum in the region of 75–125°С for the high-Ni chlorites. In addition, the high-Ni chlorites demonstrate a gradual decrease in temperature as the nickel content increases. This correlation indicates the important role of temperature as an ore generation factor during the formation of the oxide–silicate nickel deposits that are associated with the Kolskii massif. These tendencies support the conclusion that the hydrothermal processes not only preceded lateritization, but also played a significant part in the level of nickel concentration in phyllosilicates.

Investigation of Solid Residues Obtained After Oxidized Nickel Ore Leaching

Leaching residues of oxidized nickel ores is studied. According to the results of chemical analysis, it is found that with 62% extraction of nickel into the solution residues contain, wt.%: 0.58 Ni, 0.016 Co, 14.35 Fe, 9.08 Mg, 1.96 Al, and 21.16 Si. With 89% extraction residues contain, wt.%: 0.26 Ni, 0.001 Co, 6.5 Fe, 9.12 Mg, 1.46 Al, and 26.45 Si. The grain size composition of leaching residues is studied. It is found that the amount of fine fraction (– 2.5 + 0 mm) in the residues with 89% extraction almost doubles compared with the initial ore, and the amount of coarse fraction (– 21.5 + 10 mm) is halved. X-ray phase and X-ray microanalysis methods are used in the work to study residues from leaching oxidized nickel ores (ONO). With extraction of 62% of nickel from ONO nickel is detected predominantly in talc, iron oxides, and siliceous iron oxides. Nickel is not detected in leaching residues with 89% recovery.

An impact of the molar ratio of Na2O/K2O on nanomechanical properties of glaze materials containing zirconium oxide

In this paper the nanomechanical properties of three groups of glass-ceramic materials were measured. The materials designated from the multicomponent system: SiO2-Al2O3-CaO-MgO-Na2O-K2O and the difference between them was the molar ratio of sodium oxide to potassium oxide, equal to, respectively 5.45; 1.19; and 0.77. Zirconium oxide was added to those materials, in three different amounts (1.5; 3; 6 wt%). The obtained materials were characterized by the XRD method. The materials were also observed by means of a scanning electron microscope. The chemical compositions of amorphous and crystalline phases were analyzed by the EDS measurements. It has been discovered that the amorphous phase contains small amounts of zirconium cations, which positively affect its mechanical properties as confirmed by the results of a nanomechanical study. In addition, the presence of zirconium silicate and zirconium oxides in the phase composition improves mechanical properties. It was also shown that the molar ratio of alkali oxides (sodium oxide to potassium oxide) influences the amount of crystalline phase, i.e. mainly zirconium silicate. Sodium oxide, in contrast to potassium oxide, promotes the formation of more crystals in the analyzed materials and improves nanomechanical properties.

Spatial beam self-cleaning in multimode lanthanum aluminum silicate glass fiber

We demonstrated that spatial Kerr beam self-cleaning can be obtained in a highly multimode multicomponent optical fiber based on lanthanum aluminum silicate oxide glasses (SiO2-Al2O3-La2O3), which was made by using the modified powder in tube technology (MIPT). We show how such fabrication method can provide interesting potentialities to design doped multimode optical fibers with homogeneous and quasi-parabolic refractive-index core profile for nonlinear optics applications.

Clinical and radiographic evaluation of different materials in primary molar pulpotomies: A retrospective study

For proper primary teeth space to be secured and full function of primary dentition maintained, when there is deep caries found in primary teeth, pulpotomy has been quite a good choice among vital pulp therapies with a predictable success rate found in the past clinical trials.1 The objective of primary tooth pulpotomy which is usually composed of coronal pulp removal, dressing of medicament and final restoration for coronal seal,2,3 is to preserve vitality of pulp tissue in the roots and let the tooth exfoliate naturally. Agents were used in pulpotomy like formocresol (FC) and MTA.1,4, 5, 6 MTA is composed of tricalcium silicate, tricalcium aluminate and tricalcium oxide and silicate oxide and introduced by Torabinejad in 1993.7 MTA has many advantages such as good biocompatibility and sealing ability,8 antibacterial effect9 and low cytotoxicity. Also, MTA helps to induce hard tissue formation from pulp tissue.10,11 These above-mentioned characteristics showed that MTA is suitable for pulpotomy.9, 10, 11, 12 In the past studies the success rate between MTA and FC has been investigated, some concluded no significant differences between the two materials, whereas others found one material might be more suitable than the other for pulpotomy.5,13,14 SavDen MTA (Taipei, Taiwan), with improved handling property and shortened setting time,15,16 has been introduced as an alternative to ProRoot MTA for the resemblance of the composition and demonstrated similar characteristics to ProRoot MTA. Further clinical studies are needed for reveal the difference between SavDen MTA, ProRoot MTA and FC. The aim of this study was to compare the clinical and radiographic success rate of pulpotomy with SavDen MTA, ProRoot MTA and FC.

A review on high temperature resistant polyimide films: Heterocyclic structures and nanocomposites

Abstract Polyimide (PI) films are used in a wide spectrum of high-tech fields including photovoltaics , microelectronics, and aerospace engineering thanks to their good heat resistance, large mechanical strength, and low thermal expansion coefficients. Further improving their temperature resistance is expected to expand its applications. However, great challenges still exist in the fabrication of PI film with high thermal stability and good combined properties. This review summaries the design strategies and synthesis route of high thermal stability PI films, and discusses the recent progress on improving the thermal stability of PI films by nanocomposite modification. Especically, reported results by introducing a heterocyclic ring into the polymer chain to improve thermal stability were presented. Inorganic particles such as layered silicate, nitrides or metal oxides , carbon nanotubes (CNTs) and graphene used to make organic/inorganic nanocomposite for PI modification were also discussed.

Effect of Different Additives on Reaction Characteristics of Fluorapatite During Coal-Based Reduction of Iron Ore

In the coal-based reduction of high phosphorus oolitic hematite, it is particularly important to study the mechanism of phosphorus regulation during the formation of iron metals for the efficient development and utilization of iron ore. In this study, the thermodynamics of the coal-based reduction process of fluorapatite in different mineral systems, effect mechanism of the reduction degree, kinetics, mineral composition, and morphology of structural evolution samples were systematically investigated using FactSage software, single factor analysis, the isothermal method, X-ray diffraction (XRD), scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS). Thermodynamic analysis indicates that the effect of the SiO2–Fe2O3–C system on reducing the initial reduction temperature of fluorapatite was stronger than that of the Al2O3–Fe2O3–C system. The effect mechanism of the reduction degree demonstrates that increasing the dosage of silica, iron oxide, carbon, reduction time, and reduction temperature could promote the reduction reaction of fluorapatite under certain conditions. Dynamics analysis shows that the best kinetic mechanism functions of the SiO2–Fe2O3–C system and the Al2O3–Fe2O3–C system were A1/3 = 1/3(1 − α)[−ln(1 − α)]−2 and A1/2 = 1/2(1 − α)[−ln(1 − α)]−1, respectively. The activation energy and pre-exponential factor of the reduction kinetics equation in the system containing silica were significantly lower than that in the system containing alumina, which explained that the catalytic effect of silica on the reduction of calcium fluorophosphate was far greater than that of alumina. XRD and SEM/EDS analysis indicate that the solid–solid reaction of alumina, silica, iron, and fluorapatite occurred during the reduction process, while calcium aluminate, calcium silicate, and calcium oxide were formed at the contact point. Among them, iron could absorb P2 gas so that it played a greater role in promoting the reduction of fluorapatite. Increasing the reduction temperature and prolonging the reduction time were beneficial to the reduction of fluorapatite.