Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

Pang, Hongyin; Lu, Ruifang; Zhang, Tao; Lü, Li; Chen, Yanxiao; Tang, Shengwei

doi:10.1016/j.cjche.2020.02.009

Cited by 19 publications

(14 citation statements)

References 26 publications

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“…The sulfuric acid leaching method is the significant processes for producing titanium dioxide from ilmenite owing to its low requirements for feed grade 4 . In China, more than 90% of titanium dioxide is yielded by the sulfuric acid leaching method, and the production of 1 ton of titanium dioxide engenders about 8 tons of titanium white waste acid with a H 2 SO 4 concentration of about 20 wt%, 20–70 g/L of FeSO 4 5,6 . At present, titanium white waste acid is usually disposed by neutralization with lime or limestone, 7 which not only produces red gypsum, an industrial by‐product what the mainly component is calcium sulfate dihydrate and hydroxides such as iron, titanium, and magnesium, but also wastes metals resources 8,9 .…”

Section: Introductionmentioning

confidence: 99%

“…4 In China, more than 90% of titanium dioxide is yielded by the sulfuric acid leaching method, and the production of 1 ton of titanium dioxide engenders about 8 tons of titanium white waste acid with a H 2 SO 4 concentration of about 20 wt%, 20-70 g/L of FeSO 4 . 5,6 At present, titanium white waste acid is usually disposed by neutralization with lime or limestone, 7 which not only produces red gypsum, an industrial by-product what the mainly component is calcium sulfate dihydrate and hydroxides such as iron, titanium, and magnesium, but also wastes metals resources. 8,9 It is worth noting that in addition to a large amount of iron, titanium white waste acid is also rich in 2-5 g/L titanium.…”

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confidence: 99%

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Recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low‐grade pyrolusite using raffinate

Feng

2022

Asia-Pacific J Chem Eng

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Titanium dioxide industry produces a large amount of titanium white waste acid every year. In this work, to make full use of and recover valuable components in titanium white waste acid, a processing for recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low-grade pyrolusite using raffinate was proposed. After a two-stage countercurrent extraction, 99.93% Ti was extracted, while 6.51% Fe, .11% Mg, .06% Mn, and .08% Al were co-extracted under N1923 concentration of 25% and phase ratio (O/A) of 2/1. The scrubbing efficiency of iron reached 98.53%, while the loss efficiency of titanium was only .94% with 1.5 mol/L sulfuric acid solution under the phase ratio of 1/1. Then, the Ti-loaded organic phase could be effectively stripped by .8 mol/L ammonia water; the single-stage stripping efficiency of titanium was 99.23%. Subsequently, the raffinate could be used for the extraction of manganese from low-grade pyrolusite. The leaching efficiency of manganese was 99.39% at the S/L ratio of 48.00 g/L, leaching temperature of 50 C, and leaching time of 40 min. In addition, thermodynamic calculations revealed that the titanium extraction process by N1923 from titanium white waste acid was an exothermic reaction. The proposed approach is suitable for co-recovery of titanium from titanium white waste acid and manganese from low-grade pyrolusite.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low‐grade pyrolusite using raffinate

Feng

2022

Asia-Pacific J Chem Eng

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“…It is estimated that 40% of the sulfuric acid used in the SP is eventually released into the environment . As for the acid recovery from the aforementioned effluent, so far, several methods including solvent extraction, , evaporation, and membrane separation , have been investigated, but none was proved economically viable for the titanium pigment industry.…”

Section: Introductionmentioning

confidence: 99%

Development of a Safe and Environmentally Friendly Sulfate Process for the Production of Titanium Oxide

Sadeghi

Esfahany

2022

Ind. Eng. Chem. Res.

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The current research was aimed at developing a safe and more environmentally friendly sulfate process for the production of titanium oxide. In this process, to leach titanium from ilmenite by relatively dilute sulfuric acid (50 wt %), a two-step leaching scheme using a series of stirred tank reactor (STR) and vertical stirred media reactors (SMRs) was devised for carrying out the chemical reaction and particle activation, respectively. The proposed modified sulfate process (MSP) efficiency was 76.5%. The amount of sulfuric acid discarded (100 wt %) from the hydrolysis step per ton of TiO2 was about 100 kg, while this is about 1000 kg in the conventional sulfate process. About 600 kg of quick lime per ton of TiO2 is also saved in the waste acid neutralization section, which ultimately reduces the production of scrap gypsum by about 1700 kg/ton TiO2. The cost balance indicated that processing by the MSP brings about 185 US $/ton TiO2 profit.

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“…4 Acidic wastewater mainly contains 20-25% sulfuric acid (mass fraction) and 30 g/L ferrous ion, in addition to 2-5 g/L titanium and small amounts of magnesium, aluminum, and manganese. 10,11 At present, acidic wastewater is usually disposed of by neutralization with lime or limestone, which not only produces red gypsum but also wastes metal (titanium, magnesium, and aluminum) resources. 11,12 A large amount of red gypsum is dumped in the tailing pond close to the titanium dioxide plant without any treatment, posing a huge hazard to the surrounding environment.…”

Section: Introductionmentioning

confidence: 99%

“…For every ton of titanium dioxide produced, 8–10 tons of acidic wastewater is inevitably produced, of which 25–35% is returned to the titanium dioxide production process for reuse, and 6–6.5 tons of acidic wastewater produced for 1 ton of titanium dioxide is discharged 4 . Acidic wastewater mainly contains 20–25% sulfuric acid (mass fraction) and 30 g/L ferrous ion, in addition to 2–5 g/L titanium and small amounts of magnesium, aluminum, and manganese 10,11 . At present, acidic wastewater is usually disposed of by neutralization with lime or limestone, which not only produces red gypsum but also wastes metal (titanium, magnesium, and aluminum) resources 11,12 .…”

Section: Introductionmentioning

confidence: 99%

Extraction of valuable metals from acidic wastewater and blast furnace slag by a collaborative utilization process

Feng

2022

Asia-Pacific J Chem Eng

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Two typical wastes, acidic wastewater and titanium‐bearing blast furnace slag, are generated in the smelting process of vanadium‐titanium magnetite. Generally, the acidic wastewater is neutralized by lime or limestone and titanium‐bearing blast furnace slag is directly stacked in the tailings pond, which not only pollutes the ecological environment but also causes the waste of metal resources. In this study, a collaborative utilization process for efficient extraction of titanium, iron, magnesium, and aluminum from acidic wastewater and low titanium‐bearing blast furnace (LTBBF) slag was proposed. At the leaching temperature of 80°C, the leaching time of 50 min, and the liquid–solid ratio of 9:1, 99.26% Ti, 99.47% Mg, and 99.45% Al could be extracted from LTBBF slag by acidic wastewater. Leaching residue mainly composed of Ca and Si could be used as silicon fertilizer. The Ti in the leaching solution could be separated by adding Na3PO4. The precipitation efficiency of Ti reached 98.53% under the molar ratio of Na3PO4 to TiO2 of 1.4, reaction temperature of 85°C, and reaction time of 40 min. The titanium phosphate ((TiO)2P2O7) was obtained by calcination of the precipitate at 900°C for 3 h. Adding oxalic acid to the filtrate above, the precipitation efficiency of Fe, Mg, and Mn reached 96.47%, 99.21%, and 99.45%, respectively, under the optimal conditions, while the precipitation efficiency of Al was only .38%. By adjusting the pH of the filtrate to 6.5, 99.83% Al could be precipitated as Al(OH)3, and the final solution was evaporated to obtain Na2SO4 products. The method proposed realizes the harmless treatment of acidic wastewater and LTBBF slag and recovers the metal resources in both of them.

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Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

Cited by 19 publications

References 26 publications

Recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low‐grade pyrolusite using raffinate

Recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low‐grade pyrolusite using raffinate

Development of a Safe and Environmentally Friendly Sulfate Process for the Production of Titanium Oxide

Extraction of valuable metals from acidic wastewater and blast furnace slag by a collaborative utilization process

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