Wet-process Phosphoric Acid Research Articles

Feed Monocalcium Phosphate Derived from Wet-process Phosphoric Acid and Calcium-based Raw Materials

In this study, granulated feed-grade monocalcium phosphate was produced using highly purified wet-process phosphoric acid (WPA) and finely milled limestone (99.5% CaCO3). The WPA was desulfated to 0.09–0.14% SO₃, defluorinated to 0.18–0.20% F, and concentrated to 50.55% P₂O₅. Under controlled conditions—achieving a 95% reaction rate and a 15-minute decomposition time—a high-quality product was obtained. The final composition included 50.45% digestible P₂O₅, 38.02% water-soluble P₂O₅, 21.14% total CaO, and 14.39% water-soluble CaO, with a fluoride content of 0.16%. The granules achieved 2.13 MPa in strength, with over 85% in the optimal 2-3 mm size range, meeting GOST 23999-80 standards. This phosphate supplement offers high bioavailability for livestock, poultry, and aquaculture.

Integrating a high-energy activation method for the sustainable treatment of iron smelting slag, phosphogypsum, and arsenic-contaminated water

Metallurgy is one of the pillar industries in China, but metallurgy inevitably produces a large amount of industrial solid waste and heavy metal pollution. Phosphogypsum (PG) is a by-product of the production of wet-process phosphoric acid, and after the preliminary fieldwork, there is a very small amount of arsenic [As(V)] in some of the phosphorus ores, and there is a risk of heavy metal pollution. In the present study, the preparation of arsenic adsorbent (PG/IS) by doping iron smelting slag (IS) with PG as a base material was proposed and the preparation conditions were optimized by Response Surface Methodology. PG/IS was systematically characterized and its adsorption properties were investigated with respect to a variety of factors. PG/IS exhibits spontaneous endothermic chemical adsorption characteristics for As(V)，its adsorption process is more consistent with the pseudo-second-order kinetic model. Coordination complexation and chemical precipitation are the primary mechanisms by which PG/IS removes As(V). This study provides a new approach for phosphorus chemical enterprises to achieve green development and reduce industrial solid waste and As(V) emissions.

Soil utilization of solid waste: Small-strain dynamic properties and microscopic mechanism of phosphogypsum-modified coastal cement soil

Phosphogypsum (PG), a solid waste from the wet process phosphoric acid industry, but the utilization rate is low at present. The effect of phosphogypsum and cement on small strain dynamic characteristics of coastal soft soil was studied by resonance column test, and characterize the micro-mechanisms of the specimens by SEM and EDS test. The results show that the dynamic shear modulu (G) and the damping ratio (D) firstly increase and then decrease with the PG level increasing. PG can motivate the formation of hydrated calcium silicate (C–S–H) gel and react with calcium aluminate to form calcium. The critical value for assessing the dynamic behavior of PCS under small strain is γ = 10−4. The Hardin-Drnevich model eigenmodel can well characterize the dynamics of the PCS. Based on this model, a modified dynamic model is established to describe the dynamic characteristics of PCS. The microscopic results showed that the addition of phosphogypsum promoted the production of hydration products and made the particles more closely arranged. The content of this study provides a new reference for the application of solid waste phosphogypsum in cement soil.

Advances in Phosphogypsum Calcination and Decomposition Processes in Circulating Fluidized Beds.

Phosphogypsum (PG) is an industrial hazardous waste product discharged during wet-process phosphoric acid production. Once crystallized, the byproduct PG is filtered and separated from the liquid-phase product and sluiced to the disposal area near the production site for storage, seriously threatening the harmonious symbiosis between humans and nature. Therefore, devising effective solid waste management and cleaner production programs to contain and eliminate PG is of interest to researchers. In this study, the utilization status of PG is comprehensively reviewed, and a feasibility pathway for resourceful recovery of PG is proposed. The key challenges and countermeasures for the high-temperature calcination and decomposition of PG are analyzed and discussed. The visualization analysis based on bibliometrics reveals that the maximum recovery of abundant calcium (as CaO) and sulfur (as SO2) in PG and their utilization for the copreparation of calcium-based materials and sulfuric acid are the most suitable solutions for the large-scale application of PG. Five challenges that restrict the commercial promotion of PG calcination and decomposition processes are perfecting the calcium-sulfur conversion mechanism, establishing a process strengthening strategy, developing value-added technology routes, mastering unit scale-up regularity, and conducting sustainable performance assessment. Industrial applications are expected within 10-15 years.

Effect of PFDTS/TiO2 Coating on Microstructure and Wetting Behavior of Phosphogypsum.

Phosphogypsum (PG) constitutes a form of solid byproduct emanating from the manufacturing process of wet-process phosphoric acid. The fabrication of one metric ton of wet-process phosphoric acid entails the generation of approximately five tons of phosphogypsum, a highly prolific and economically viable waste stream. If we can effectively solve the problem of poor hydrophobicity of phosphogypsum, it is possible to replace cement and other traditional cementitious materials. In this way, we can not only improve the utilization rate of phosphogypsum but also obtain significant economic and environmental benefits. In the present investigation, hydrophobic surface coatings were synthesized and applied onto the surface of α-hemihydrate phosphogypsum (α-HPG) utilizing sol-gel processing and impregnation techniques. After hydroxylating α-HPG with alkaline solution (OH-α-HPG), titanium dioxide nanoparticles (TiO2) hybridized with perfluorodecyltriethoxysilane (PFDTS) were grafted on its surface. The assessment of the hydrophobic properties of the coatings was conducted through water contact angle measurements, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) analyses. The contact angle remained above 124.2° after strong acidic and alkaline immersion and 50 tape adhesion experiments with good chemical stability and durability, and the mechanism of surface hydrophobicity modification was discussed. The experimental outcomes demonstrated a notable increase in the hydroxyl group concentration on the α-HPG surface following hydroxylation, significantly enhancing the attachment rate of PFDTS and TiO2 onto the HPG surface. PFDTS and TiO2 can undergo chemical interaction with hydroxyl groups, facilitating their robust adsorption onto the surface of OH-α-HPG through chemisorption mechanisms. After bonding the OH-α-HPG surface with PFDTS and TiO2 via hydrogen bonding, the otherwise hydrophilic α-HPG surface acquired excellent hydrophobicity (OH-α-HPG-PT, contact angle (CA) = 146.7°). The surface modification of α-HPG through hydroxylation and hydrophobicity enhancement significantly augmented the compatibility and interfacial interplay between α-HPG and PT. This research successfully enhanced the hydrophobic properties of α-HPG, profoundly showcasing its immense potential within the construction industry and the realm of comprehensive solid waste utilization.

“Treating Waste with Waste”: Utilizing Phosphogypsum to Synthesize Porous Calcium Silicate Hydrate for Recovering of Fe2+ from Pickling Wastewater

Phosphogypsum is a by-product of the wet-process phosphoric acid production, and it is rich in Ca and S. Long-term storage of Phosphogypsum can cause serious pollution to the environment; therefore, promoting the sustainable utilization of Phosphogypsum is crucial. This study proposes the use of Phosphogypsum and silicic acid in a sodium hydroxide solution for the hydrothermal synthesis of porous calcium silicate hydrate adsorbent, which is used for adsorbing Fe2+ from simulated hydrochloric acid pickling wastewater. Under the optimal synthesis conditions (37.5 g/L of NaOH, calcium/silicon ratio of 1.0, liquid/solid ratio of 15:1 mL/g, 110 °C, and 4 h), the conversion rate of SO42− in Phosphogypsum is 87.41%. Porous calcium silicate hydrate exhibits excellent OH− release capability in Fe2+-containing pickling wastewater. The adsorption process for Fe2+; is mainly chemical adsorption, involving ion exchange between Ca2+ and Fe2+, as well as complexation reactions of O-Si-O group, -OH group, and Si-O group with Fe2+. This technology aims to provide a solution for the sustainable utilization of Phosphogypsum and the recovery of Fe2+ from pickling wastewater, which has significant practical importance.

Removal of magnesium and aluminum from wet phosphoric acid by ralstonite precipitation: Thermodynamic and performance analysis, mechanistic studies and precipitate characterization

The purification of wet-process phosphoric acid has always posed a challenge for both academic and industrial researchers. In order to address this issue, a treatment unit was developed to mitigate magnesium and aluminum impurities from industrial semi-aqueous wet process phosphoric acid (SWPPA) (39.4 wt% P2O5) through ralstonite precipitation using Na+/F− as the precipitator (F− provided by HF). Thermodynamic analysis, DFT calculation and separation experiments results were used to investigate the impact of sodium sources properties on impurities removal rates and H3PO4 yield. Additionally, the effects of reaction temperature, reaction time, precipitating agent dosage, and aging time on precipitation efficiency were also examined. The results show that the ability of sodium source to ionize Na+ and react with H3PO4 and HF plays a crucial role in determining the impurity removal performance of magnesium and aluminum. The precipitants NaCl and Na2CO3 exhibit the highest removal rates for magnesium and aluminum, which is attributed to the easy ionization of Na+ ions. In comparison to Na2CO3, the higher H3PO4 yield with NaCl as precipitator can be achieved due to its lower nucleation rate and higher crystal growth rate in the phosphoric acid system. NaCl and HF as precipitants effectively reduces the concentrations of magnesium and aluminum in the untreated SWPPA solution from 23.47 g MgO/kg P2O5 to 3.29 g MgO/kg P2O5, 48.98 g Al2O3/kg P2O5 to 15.54 g Al2O3/kg P2O5. The removal rates for magnesium and aluminum are found to be 85.98% and 68.27%, respectively, with minimal residue of Na+/F−.

Advanced magnetic adsorbents for enhanced phosphorus and fluoride removal from wastewater: Mechanistic insights and applications

A novel mesoporous magnetic nanoparticle adsorbent, Fe3O4@CSH-AAO, was synthesized using the atomization-precipitation method, effectively removing phosphorus (P) and fluoride (F) from wastewater, particularly from the recirculating water of wet-process phosphoric acid. The adsorbent achieved removal efficiencies of 99.6 % for P and 73.5 % for F under conditions of 20 g/L adsorbent dosage, pH ≈ 4, with initial P and F concentrations at 115 mg/L and 38 mg/L, respectively. Equilibrium adsorption data indicated that the adsorption kinetics followed the pseudo-second-order model for F and the pseudo-first-order model for P. The adsorption isotherms fitted the Langmuir model for P and the Freundlich model for F, with maximum adsorption capacities of 37.86 mg P/g and 6.764 mg F/g at pH 4 and 298 K. The surface properties, functionality, and crystallinity were analyzed using BET, SEM, TEM, XRD, and XRF. Furthermore, XPS analyses and molecular dynamics (MD) simulations elucidated that surface Ca in CSH and the exposed Al atoms on the γ-Al2O3 (110) surface serve as optimal adsorption sites for P and F. The steric hindrance imposed by phosphorus contributes to its preferentially higher adsorption capacity over fluoride. This study not only presents an effective method for the removal of phosphorus and fluoride suitable for practical applications but also provides deep insights into the adsorption mechanism, highlighting the pivotal role of steric hindrance in facilitating ion adsorption.

Studies on uranium sorption from Egyptian wet-process phosphoric acid using silicone rubber modified with thiourea and methyl methacrylate composite

ABSTRACT The application of silicone rubber modified by thiourea and methyl methacrylate composite SRTM aimed at the sorption of uranium from commercial phosphoric acid is the highest objective of this examination effort. The impact of various factors on sorption efficiency for example adsorbent dose (g/ml), temperature, phosphoric acid concentration, and shaking time have remained studied. XRD, XRF, EDX, SEM, Zeta potential, BET, and FTIR analyses remained carried out to determine the properties of the produced composite. The attained results showed the sorption capacity for uranium as 25.19 mg g− 1 at the mentioned conditions; commercial phosphoric acid, 30% P2O5, 120 min, and room temperature. The investigational documents have been designated fine with pseudo-second-order kinetic scientific calculations. Balance process described by isotherm model’s Langmuir. uranium sorption thermodynamic considerations showed a spontaneous procedure and exothermic nature (ΔG (kJ/mol) = −13.8:-11.3, ∆H(kJ/mol) = −34.9, ∆S (J/mol K) = −70.9). Mechanism and reusability sorption were studied and Desorption efficiencies of about 95% for U (VI) were achieved using 1.0 M sulphuric acid solution.

Study on the preparation of high-concentration ammonium phosphate suspension fertilizer from wet-process phosphoric acid and its rheological properties

BackgroundNew water-soluble fertilizer can be applied to modern irrigation systems and has significant advantages. This study uses wet-process phosphoric acid as raw material and chelation and suspension technology to prepare water-soluble fertilizer containing high-concentration ammonium phosphate. MethodsFirst, the composition and viscosity of the wet-process phosphoric acid was analyzed, and the ammoniation and chelation processes were explored. Subsequently, four suspension formulations were compared and selected after product analysis. The final process conditions are: 42 wt % (P2O5 %) phosphoric acid, 20 wt % chelating agent, pH = 4.5, 0.03 wt % xanthan gum or 0.02 wt % carboxymethyl cellulose of respectively, and obtain suspension fertilizer by high-speed shearing. Significant FindsThe Bingham model and Casson model were used to fit the rheological data of the two, and R2 values were greater than 0.94. The thixotropic loops of the two were measured using the triangular shear rate variation method mode, and the Huang equation and MBM models were used to fit the thixotropic loop data of the two respectively. In addition, at different pH and temperature, the suspended fertilizer performed well.

Experimental study on the mechanism and thermodynamics of extraction of Fe3+ from phosphoric acid solution

The new extractant (P12) was used to remove Fe3+ from the simulated liquid of wet process phosphoric acid in this work. The solubility of P12 in white oil under the action of P204(Di-(2-ethylhexyl) phosphate) and n-octanol is discussed in detail. Then, the effects of reaction temperature, reaction time, the volume ratio of extraction phase and aqueous phase (O: A), pH of the phosphoric acid solution(simulated solution) and various anions on the extraction process were discussed. The extraction efficiency increases with the increase of extractant P12, the decrease of pH and the increase of O: A. Under the condition of pH=0.2, O: A= 1:1, the extraction efficiency of P12=5 %, 7 % and 9 % can be up to 70.86 %, 81.84 % and 90.93 % respectively. The extraction mechanism and extract composition were determined by slope method, FTIR and SEM. The ΔH< 0, ΔG< 0, ΔS < 0 in the extraction process proves that the extraction process was a spontaneous and exothermic process. The extraction mechanism proves that the extraction process involves both cation exchange and complexation of extractant. The composition of the extract may be [Fe(H2PO4)2.4A0.6(HA)0.84(H2O)](o), [Fe(H2PO4)2.2A0.8(HA)1.12(H2O)](o). And stripping efficiency of 5.5 M HCl can reach 100 % at A: O=4:1, ΔH=38.9357 kJ/mol in stripping process prove that it is endothermic.

Recovery of Iron Resources from Wet-Process Phosphoric Acid and the Preparation of High Purity Ferrous Oxalate: Solvent Extraction and Photochemical Reaction

Recovery of Iron Resources from Wet-Process Phosphoric Acid and the Preparation of High Purity Ferrous Oxalate: Solvent Extraction and Photochemical Reaction

Closed-loop purification process of industrial phosphoric acid: Selective recovery of heavy metals and rare earth elements via solvent extraction

Phosphate fertilizers are produced using phosphoric acid as a vital chemical component. This essential ingredient is typically derived from phosphate rock, through a wet process phosphoric acid (WPPA). However, the WPPA contains impurities, including heavy metals (HMs) like cadmium (Cd), zinc (Zn) and copper (Cu), as well as unwanted elements like iron, and other valuables elements, notably rare earth elements (REEs) such as yttrium (Y), holmium (Ho) and ytterbium (Yb). The current study aims to develop a novel process for a simultaneous and selective recovery of HMs and REEs through solvent extraction from WPPA. Single-stage extraction, cascade extraction and synergistic extraction were explored to gain a deeper understanding of the mechanisms and identify the most efficient process. 90, 80 and 99 % for Y, Ho and Yb, respectively, were extracted using D2EHPA. While 89 % for Zn, 99 % for Cu and Cd were removed using Cyanex 301. On the other hand, 60 % of Yb, 74 % of Y and 78 % of Ho were stripped using H2SO4, while 98 % of Cd and 99 % of Zn were stripped using HCl. The organic phase can be successfully reused with an effective extraction and stripping. Oxalic acid (C2H2O4) was employed to precipitate REEs. However, sodium carbonate (Na2CO3) was used to precipitate HMs. Finally, solvent extraction was carried out on WPPA solution to ensure the extraction performance under industrial conditions.

Recovery of uranium from phosphate ore of Iran mine: Part II- solvent extraction of uranium from wet-process phosphoric acid

The current study in laboratory scale was aimed at developing an optimal two-stage extraction process for production of yellow cake from the phosphoric acid solution that was extracted from the Sheikh Habil phosphate rocks in central Iran. To attain an optimized extraction process, different mixtures of D2EHPA + TOPO + TBP were examined. A total extraction cycle including extraction, stripping and yellow cake precipitation was run to realistically evaluate the performances of the selected mixtures-conditions. As for optimization of the operational conditions, we exploited central composite design (CCD) method, that is a branch of the surface response methodology (RSM), and analyzed the results with standard statistical methods. The O/A (organic to aqueous ratio) = 2, 11 min extraction time, 5 wt% TOPO concentration, 10–15 wt% TBP concentration, 20 wt% D2EHPA concentration, 800 mv oxidation-reduction potential, and 25 °C temperature were obtained as optimum extraction parameters. The O/A = 15, 11 min stripping time, 50 wt% phosphoric acid concentration, 250 mv oxidation-reduction potential, and 40 °C temperature were obtained as optimum stripping parameters. Finally on the last uranium extraction from the H3PO4 strippant on the optimum conditions, the concentration of uranium was more than 4500 ppm with extraction efficiency near to 90 %. Scrubbing of organic phase was done by 2 wt% of sulfuric acid solution at 40 °C and precipitation of ammonium uranyl carbonate (AUC, (NH4)4UO2(CO3)3) was done with 2 M ammonium carbonate solution at an O/A ratio of 1/2 with efficiency more than 95 % in the uranium precipitation process.

Utilization of methyltrichlorosilane as a novel and efficient reagent to enhance fluorine recovery from wet-process phosphoric acid

Recovering fluorine from wet-process phosphoric acid (WPA) by the evaporation concentration method has been widely used due to its simplicity and cheapness. However, the low fluorine recovery reduces the WPA quality, which in turn has detrimental effects on fertilizer production and leads to a waste of valuable fluorine resources. In this work, a cost-effective organic liquid, methyltrichlorosilane (MTS), was first employed as the gasification reagent in the WPA concentration process to promote fluorine recovery. The effects of several important parameters including MTS dosage, initial mass of absorptive water, addition stages, stirring speed, and concentration temperature, were investigated. The first three factors emerged as pivotal determinants of the fluorine recovery and the results revealed a remarkable 87.94% recovery of fluorine from WPA, signifying a substantial enhancement compared to the recovery achieved in the absence of MTS, which amounted to 40.36%. The defluorination kinetics data was well-fitted with a second-order model, and showed an activation energy of 23.77 kJ/mol, highlighting the strong interaction between MTS and fluorine in WPA. In addition, liquid MTS could recover fluorine selectively and efficiently without compromising the quality of WPA and exhibited superior fluorine recovery when compared to traditional solid mineral reagents such as diatomite and white carbon black. Further analysis revealed the governing mechanism for fluorine recovery that the addition of MTS prevented the conversion of liquid HF and H2SiF6 to solid Na2SiF6 and K2SiF6, favoring SiF4 gas production. Overall, this research provides valuable insights for enhancing fluorine recovery during the WPA concentration process and developing environmentally friendly reagents.

Efficient recovery of fluorine from wet-process phosphoric acid using silicon powder as a new and eco-friendly reagent

The recovery and utilization of fluorine resources from wet-process phosphoric acid (WPA) is of great importance in protecting environment and providing cheap raw materials for the fluorine chemical industry. Evaporation concentration method is widely used due to its simplicity and low operating expenses. However, the lack of effective reagents limits the further development. In this study, silicon powder (SP) was firstly used to enhance the fluorine recovery during the concentration process of WPA. The gasification performance and behavior in reaction system (SP dosage, stirring speed, and concentration temperature) and absorptive system (initial mass of absorptive water) were investigated in detail. The results showed that SP had an excellent performance for fluorine recovery, which was superior to traditional reagents like diatomite, white carbon black (WCB) and zeolite powder (ZP). Under the optimal conditions, the fluorine recovery could reach an impressively high percentage of 81.13%, exhibiting a significant increase of 31.08% compared with blank concentration. Furthermore, SP could selectively and efficiently recover fluorine without affecting the quality of WPA. Spillover kinetics suggested that the rate of reaction between SP and fluorine was slow, with an apparent reaction order of 0.56. During the concentration process of WPA, SP showed a better tendency to react with H2SiF6 and HF. The addition of SP could increase the production of SiF4 gas and reduce the formation of fluorine precipitates. These two pathways are responsible for the improvement of fluorine recovery. Overall, this research provides a valuable reference for the efficient recovery of fluorine from WPA.

Enhanced absorption of SO2 from phosphogypsum decomposition by phosphate slurry for phosphoric acid production

Phosphogypsum (PG) is a major industrial by-product of wet process phosphoric acid production, and untreated PG stockpiled on land will cause severe environmental pollution. Thermal treatment of PG is currently the mainstream treatment method PG can be thermally decomposed to produce CaO, and the decomposition process produces large amounts of SO2. In this paper, phosphate slurry was used to absorb SO2 generated during the PG decomposition to produce phosphoric acid. The effects of operating conditions such as pressure, inlet SO2 concentration, and additive content on the desulfurization efficiency, as well as phosphoric acid yield, were investigated. Under the optimal experimental parameters, the desulfurization efficiency was 100% in the first 3 h, and decreased to 67.42% after 5 h, the maximum phosphate concentration in the solution was 1445.92 mg/L. The Density functional theory (DFT) calculations showed that SO2 and O2 adsorbed on the surface of P2O5 underwent to generate SO3, which can react with H2O to produce H2SO4. Moreover, it was found that Fe3+ could enhance the catalytic oxidation process of SO2 and O2 by decreasing the reaction energy barrier. This study should be helpful for the recycling of phosphorus resources.

Obtaining ammophosphate and sulfoammophosphate fertilizers on base of the washed dry concentrate containing 26% P2O5

The process of obtaining ammophosphate by means of phosphoric acid decomposition of washed dried concentrate (WDC with 26% P2O5 and 10% CO2) - raw material for the production of thermally fired concentrate, has been studied. The wet process phosphoric acid (WPA) contains (wt.%): 16.46 P2O5, 0.06 CaO, 1.11 MgO, 0.27 Fe2O3, 0.41 Al2O3, 2.98 SO3 and 0.99 F. The weight ratio of WPA:WDC ranged from 100: 10 to 100: 30. Then acidic phosphate pulps (at 65 °C) after 45 minutes were ammoniated to pH = 3.8, granulated and dried at 85-90 °C. It has been shown that the nitrogen content in the finished product ranges from 4.92-7.11%, total phosphorus (P2O5t.) 41.48-46.44%, phosphorus acceptable by citric acid (P2O5ac.c.a.) 34.79-45.11%, phosphorus form of water soluble (P2O5w.s.) 23.49-37.73%. Weight fractions of H2SO4 - 5 and 7.5 were optimal and the product contains 37.6 and 34.47% of P2O5t.; 24.11 and 22.06% CaOt., 88.75 and 92.40% P2O5ac.c.a.by citric acid: P2O5t., 84.21 and 89.7% P2O5ac.tr.b. by trilon B: P2O5t., 77.39 and 79.54% P2O5w.s.:P2O5t., 6.03 and 7.08% nitrogen, respectively. The strength of granules of fertilizers averages 3.50 MPa and are quite suitable for bulk storage and transportation.

Study of the Process of Calcium Feed Phosphate Fabrication by Thermal Acid Processing of Washed Dried Concentrate

The process of acid-thermal treatment of washed dried concentrate in order to obtain feed calcium phosphate was studied. At the first stage, phosphoric acid decomposition of phosphate raw materials with wet process phosphoric acid was carried out at 65ºС for 30 minutes. In this case, the ratio of CaO: P2O5 = 1.67; 1.45; 1.31; 1.18; 1.00 and 0.79. In the second stage, the process of thermal roasting of acid decomposition products was carried out at temperatures of 800-1200ºС. It was shown that with a decrease in the calcium module from 1.67 to 0.79 and an increase in the firing temperature from 800 to 1200ºС, the fluorine content in the thermophosphate samples decreases from 3.09 to 0.23% and from 2.63 to 0.34%, respectively. during thermal treatment 1 and 2 hours.

磷矿硅渣合成NaA型分子筛及应用于湿法磷酸脱氟的研究

磷矿硅渣合成NaA型分子筛及应用于湿法磷酸脱氟的研究