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The fluoride recovery process included dissolution of calcium sulfate dihydrate and formation of calcium fluoride by the reaction of Ca 2+ ion and F − ion. When the initial concentration of fluoride in wastewater was 1000 mg/L, the fluoride removal efficiency of the two column reactors in series was more than 99 %.
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Fluoride recovery from the fluoride containing wastewater using CSH, which can avoid not only adding extra calcium but also adjusting pH value, can be a simple and beneficial technology. In the present paper, porous calcium silicate hydrates (P-CSH) with low crystallinity and high Ca/Si molar ratio were synthesized from unlimitedly …
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The fluoride recovery process included dissolution of calcium sulfate dihydrate and formation of calcium fluoride by the reaction of Ca 2+ ion and F − ion. …
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Fluoride removal using fluidized bed crystallization (FBC) technology with phosphate rock (PR) and calcite as seed particles under an alkaline groundwater condition was investigated. The results indicated that the optimized operating parameters were: upflow velocity = 7.21 m h −1, Ca:P:F molar ratio = 10:4:1, and initial bed height = 120 …
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Calcium fluoride (CaF 2) recovery in a fluidized bed reactor was reported by Aldaco et al. [13], [14]. To ensure fluoride removal efficiency, it is very important to control the supersaturation degree in the crystallization reactor [13].
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The removal efficiency of fluorine and recovery ratio of calcium fluoride were obtained as 93.79% and 89.45%, respectively. The particle size of recovered calcium fluoride was about 1.5mm.
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The key factor for the recovery of calcium fluoride is controlling supersaturation (Aldaco et al. 2008). However, it is not feasible to recover calcium fluoride from wastewater with high concentrations of aluminum and fluorine. Under this condition, the low supersaturation ratio cannot be maintained. In addition, aluminum hydroxide tends to ...
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The main objectives are to compare (i) the treatment efficiency, (ii) the consumption of chemical reagents, and (iii) the recovery of high-value by-products (e.g. calcium fluoride, struvite, and ...
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Semantic Scholar extracted view of "Chemical precipitation at extreme fluoride concentration and potential recovery of CaF2 particles by fluidized-bed homogenous crystallization process" by Carl Francis Z. Lacson et al. ... Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor. R. Aldaco A. Garea Á. …
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Calcium fluoride (CaF 2) is one of the main materials with a wide range of applications, based on which it is commercialized as acid-grade, ceramic-grade, and metallurgical-grade . To deal with the high consumption of natural resources, the recovery of fluoride from waste is considered a priority.
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The application direction has gradually expanded to recover fluoride, remove phosphate, recover heavy metals, and synthesize crystals. This article reviews the application of fluidized bed crystallization in water softening, fluoride recovery, phosphate removal, recover heavy metals, and synthetic crystals in recent decades.
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The recovery ratio and removal efficiency of calcium fluoride of actual wastewater (SiO 2) were determined as 89.45% and 93.97%, respectively. Compared with several other traditional methods, fluidized bed crystallization technology has a better …
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Granulated calcite and silica were used as seed materials to recover the calcium fluoride by crystallization in a fluidized bed reactor. The inlet concentration of …
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The fluoride recovery process included dissolution of calcium sulfate dihydrate and formation of calcium fluoride by the reaction of Ca 2+ ion and F − ion. When the initial concentration of fluoride in wastewater was 1000 mg/L, the fluoride removal efficiency of the two column reactors in series was more than 99 %. This work provides …
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The fluoride recovery process included dissolution of calcium sulfate dihydrate and formation of calcium fluoride by the reaction of Ca 2+ ion and F − ion. When the initial concentration of fluoride in wastewater was 1000 mg/L, the fluoride removal efficiency of the two column reactors in series was more than 99 %.
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High fluoride-content wastewater is commonly found among various industries, such as fertilizer, aluminum, and semiconductor. Its treatment was studied by using calcium precipitation followed by ultrafiltration (UF). Experimental results indicated that fluoride could be reduced from 305 mg/L to 15 mg/L by the addition of calcium …
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This report addresses issues specific to generation of hydrogen fluoride via reaction of calcium fluoride with sulfuric acid. ... predicted reaction temperatures and reactant mole ratios are reported for the recovery of hydrogen fluoride (HF), a valuable industrial feedstock. Complete conversion of MgF{sub 2} is found at 1,000 C and a ratio …
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The removal efficiency of fluorine and recovery ratio of calcium fluoride were obtained as 93.79% and 89.45%, respectively. The particle size of recovered calcium fluoride was about 1.5mm.
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The removal efficiency of fluorine and recovery ratio of calcium fluoride were obtained as 93.79% and 89.45%, respectively. The particle size of recovered calcium fluoride was about 1.5mm.
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In comparison with the crystalline calcium silicate hydrates (C-CSH), P-CSH, which has large specific surface areas of 148.11 m 2 /g, a high Ca/Si molar ratio of 2.28 and low crystallinity, exhibited a high capacity for fluoride recovery from synthetic and practical electroplating wastewater. Fluoride recovery by P-CSH continued spontaneously ...
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1. Introduction. Removal of fluoride from wastewater of semiconductor or optoelectronic industries through CaF 2 precipitation is the most common practice in Taiwan [1].Both calcium chloride and lime are used as the calcium source to promote precipitation of CaF 2.The former is preferred due to relatively less sludge generated [2].However, …
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The calcium and fluoride solutions were. Chemical precipitation of CaF 2. The chemical precipitation is the primary mechanism of coagulation-flocculation treatment and fluidized-bed granulation systems. ... Cryolite (Na 3 AlF 6) crystallization for fluoride recovery using an electrolytic process equipped with a sacial aluminum anode.
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The precipitant of calcium fluoride, suspension of lime, was prepared by mixing industrial-grade lime [Ca(OH) 2] and tap water. The industrial-grade calcium carbonate (CaCO 3) was used as the seed material for calcium fluoride recovery. The industrial-grade polymeric aluminum chloride (PAC, mass fraction of 28%) was used in …
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The key factors for the recovery of calcium fluoride are controlling the supersaturation and the fluidization of seed (Aldaco et al. 2008). The recovered calcium fluoride can be easily separated and …
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Purpose of Review To present an overview of the ongoing research on enamel and dentin remineralization and to describe particle-mediated and biomimetic approaches. The importance of restoring tissue functionality as the ultimate goal of remineralization is emphasized. Recent Findings Calcium-releasing particles and adjuvants to increase …
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The removal efficiency of fluorine and recovery ratio of calcium fluoride were obtained as 93.79% and 89.45%, respectively. The particle size of recovered calcium fluoride was about 1.5mm. The results show that FBR with silica sand as seed crystal is a feasible and economical method for removing fluorine and recovering calcium fluoride …
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Calcium fluoride doped with dysprosium is one of the most popular TL materials in use today. This material has a complex glow curve that is composed of six peaks. ... Resource Recovery and Recycling from Metallurgical Wastes. S. Ramachandra Rao, in Waste Management Series, 2006. 9.2.2 Potential Applications of Slag and Dross from …
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Effect on ceramic grade CaF2 recovery quality from the etching wastewater under the optimum sulfate content. Yin Changkai Z. Lou Haiping Yuan N. Zhu. Materials Science. 2016. The improvement of fluorite quality is an attractive measure to recover fluoride from high F− content wastewater and thus reduces the fluorite sludge …
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Fluorine removal and calcium fluoride recovery from rare-earth smelting wastewater using fluidized bed crystallization process. @article{Zeng2019FluorineRA, title={Fluorine removal and calcium fluoride recovery from rare-earth smelting wastewater using fluidized bed crystallization process.}, author={Guisheng Zeng and Bo Ling and …
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The process is based on the crystallization of calcium fluoride upon seed grains in a fluidized bed using seed grains of silica sand. ... This article reviews the application of fluidized bed crystallization in water softening, fluoride recovery, phosphate removal, recover heavy metals, and synthetic crystals in recent decades. The structure of ...
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