Novel Process For Recovery Research Articles

A novel process for recovery and exploitation of polyesters and polyamides from waste polymeric artifacts

Plastic waste is one of the world's biggest sources of pollution. Despite the growing trend towards recycling, there are currently no effective technologies to offset the continuous increase in plastic production. Polyesters and polyamides are among the most widely produced single-use plastics, mainly used in the manufacture of textiles and soft drink bottles. Currently, only a small proportion of these polymers can be effectively recycled. The two primary methods employed for this purpose are mechanical and chemical recycling. Presently, mechanical recycling remains the more widely adopted process within the industrial sector. However, the treatment process is limited to a narrow range of waste materials as it is impossible to remove dyes and the mechanical properties deteriorate due to incompatibility between different plastic materials. Another critical limit of this recycling technology is the limited number of recycling loops that can be done due to the thermal degradation that occurs during the extrusion process. The alternative option is chemical recycling, which allows the depolymerization of the original product to recover the monomers directly. The main drawbacks are the long reaction times and the many solvents needed to achieve high-purity products. As a results, chemical recycling is only economically feasible for large companies that can produce the virgin polymer in situ. In this work, a new technology has been patented. This process consists of three main steps. The first one is the distillation-assisted cyclodepolymerization (DA-CDP), introduced as a modification of the CDP process. In this unit, cyclic oligomers together with high molecular weight compounds are produced. Then, after polymer purification, it is possible to achieve the same molecular weight as the initial polymer in less than 30 min, exploiting the ring-opening polymerization (ROP) of the next step.

A novel process for recovery of scandium, rare earth and niobium from Bayan Obo tailings: NaCl-Ca(OH)2-coal roasting and acid leaching

Bayan Obo tailings from Baotou Steel were discharged into tailings pond. The advantages of symbiotic resources have not been fully played. A large number of accumulated tailings also have a great impact on the surrounding environment. Comprehensive utilization of valuable elements in tailings becomes key measure to solve the above problems. Extraction of valuable elements, such as scandium, rare earth and niobium could be achieved by roasting Bayan Obo tailings in NaCl-Ca(OH)2-coal, followed by hydrochloric acid and sulfuric acid leaching. The phase transitions of main minerals were investigated. In the roasting process, niobium minerals were converted to CaTiO3-type compounds. The original rare earth minerals turned into rare earth oxide or rare earth silicate. Iron in Sc-Fe-bearing silicate migrated to CaFeSiO4, FeSiO3 and Fe3O4. Meanwhile, the structure of silicate was destroyed completely, which facilitated for leaching scandium. In the acid leaching process, newly generated niobium minerals were dissolved in sulfuric acid as niobium sulfate or niobic acid. For Bayan Obo tailings, under the optimal roasting and leaching conditions determined in this research, 97.6% Sc2O3, 97.18% REO and 40.1% Nb2O5 entered hydrochloric acid. 51.67% Nb2O5 was leached by concentrated sulfuric acid. Sc2O3 and REO were enriched in hydrochloric acid.

A Novel Process for Recovery of Key Elements from Commercial Cathode Material of End-of-Life Lithium-Ion Battery

A Novel Process for Recovery of Key Elements from Commercial Cathode Material of End-of-Life Lithium-Ion Battery

Efficient Electrochemical Recovery of Tellurium from Spent Electrolytes by Cyclone Electrowinning

A novel process for recovery of tellurium (Te) from spent Te electrolytes by cyclone electrowinning was developed. The effects of current density, electrolysis time, flow rate of the electrolyte (FRE), electrolyte temperature and cathode substrates on current efficiency (CE), tellurium recovery, cell voltage, energy consumption (EC), and surface morphology were systematically investigated. 99.90% of purity Te deposits were obtained while 95.61% of CE was achieved under the optimum conditions: electrolysis time of 24 h, current density of 60 A·m−2, FRE of 300 L·h−1, temperature of 30 °C and cathode substrates of 316L SS. Meanwhile, Te recovery and EC were 82.89% and 1810.58 kWh·t−1, respectively. Furthermore, as the solution after the electrowinning is recyclable, the consumption of reagents and the liquid effluent are minimized. All the parameters indicate that the cyclone electrowinning technology might serve as a promising alternative for recovering Te from spent Te electrolyte.

Selective recovery of lithium and iron phosphate/carbon from spent lithium iron phosphate cathode material by anionic membrane slurry electrolysis

A simple, green and effective method, which combined lithium iron phosphate battery charging mechanism and slurry electrolysis process, is proposed for recycling spent lithium iron phosphate. Li and FePO4 can be separation in anionic membrane slurry electrolysis without the addition of chemical reagent. The leaching efficiency of Li can reach to 98% and over 96% of Fe are recycled as FePO4/C. Kinetics analysis indicates that the surface chemical reaction is the control step during the slurry electrolysis. Additionally, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Electrochemical Impedance Spectroscopy (EIS) characterization and thermodynamic analysis are employed to investigate the leaching mechanism. It is found that the spent LiFePO4 is delithiated and oxidized to FePO4 by the function of e−, which is similar as the LiFePO4 battery charging process. EIS analysis also verify the kinetics results, the charge transfer resistance controlled the leaching process. Finally, a novel process for recovery of spent LiFePO4 is proposed. The recovered Li2CO3 and FePO4/C can be used for resynthesize LiFePO4, and the resynthesized LiFePO4 exhibits reversible capacities of 143.6 mAh g−1 at 1C and high current efficiency, stable cycle performances at 0.1 and 0.5C which meets the basic requirements for reuse.

Electrodeposition of tellurium from alkaline solution by cyclone electrowinning

A novel process for recovery of tellurium (Te) from alkaline solution by cyclone electrowinning was proposed. The electrochemical behavior of Te in alkaline media was determined by cyclic voltammetry and linear sweep voltammetry measurements. It indicated that TeO32− ion was first reduced to Te(s), then to Te22− ion. It has been identified that Te electrodeposition was diffusion and charge transfer controlled irreversible reaction. The influences of Te concentration, NaOH concentration, flow rate of the electrolyte, current density and cathode material on Te cyclone electrowinning were systematically investigated. The current efficiency of 95.25% and energy consumption of 1737.59 kWh·t−1 was achieved from the electrolytes containing 100 g·L−1 Te and 100 g·L−1 NaOH at 300 L·h−1 flow rate of the electrolyte and 100 A·m−2 current density, 316 L stainless steel cathode. Te deposits with a purity of 99.94% was obtained.

A novel process for recovery of aluminum, iron, vanadium, scandium, titanium and silicon from red mud

A novel process for recovery of aluminum, iron, vanadium, scandium, titanium and silicon from red mud was proposed. The parameters of HCl leaching, solvent extraction, polymerization process, alkali leaching with pressure, and aging process were investigated. The results show that more than 96 % of scandium and vanadium could be leached by using HCl with many aluminum, iron and few titanium and silicon from red mud. More than 97 % of vanadium and scandium was extracted by solvent extraction with mono(2-cthylhexyl)2-cthylhexyl phosphonate (P507), but few other elements from the acid leaching solution. The rich vanadium liquid and rich scandium liquid could be obtained by washing the saturated organic phase. More than 97 % of iron and aluminum could be precipitated as the polyaluminum ferric chloride from the raffinate. The rich titanium material of TiO2 with grade of 62 % was obtained by NaOH leaching with pressure from the acid leaching residue. The white carbon black with purity of 99.5 % was obtained by aging with sulfuric acid solution.

A novel process for recovery of rare earth and fluorine from bastnaesite concentrates. Part I: calcification roasting decomposition

Abstract Environmental pollution and valuable resource waste exist commonly in current metallurgical processes of bastnaesite concentrates. A novel associated process of calcification roasting, mineral beneficiation and acid leaching was proposed. This paper focused on the prior calcification roasting decomposition procedure. By studying the influence of roasting conditions on cerium oxidation, the optimum technology conditions were obtained: operated at 650°C for 60 min with 20% calcium hydroxide. After roasting, the leaching rate of rare earths can reach 98.84%. Bastnaesite can be sufficiently decomposed at lower temperature with calcium hydroxide added and the emission rate of fluorine decreased by over 98% compared with that during the roasting without additives. After the roasting, the main existence form of fluorine turned calcium fluoride, which made it possible for resource utilization and environmental protection. Particle sizes and scanning electron microscope and energy dispersive spectrometer analyses indicated that rare earth oxides gathered in particles of >48 μm, while generated calcium fluoride with fluffy cotton morphology distributed evenly.

A novel process for recovery of fermentation-derived succinic acid: Process design and economic analysis

Recovery and purification of organic acids produced in fermentation constitutes a significant fraction of total production cost. In this paper, the design and economic analysis of a process to recover succinic acid (SA) via dissolution and acidification of succinate salts in ethanol, followed by reactive distillation to form succinate esters, is presented. Process simulation was performed for a range of plant capacities (13-55 million kg/yr SA) and SA fermentation titers (50-100 kg/m(3)). Economics were evaluated for a recovery system installed within an existing fermentation facility producing succinate salts at a cost of $0.66/kg SA. For a SA processing capacity of 54.9 million kg/yr and a titer of 100 kg/m(3) SA, the model predicts a capital investment of $75 million and a net processing cost of $1.85 per kg SA. Required selling price of diethyl succinate for a 30% annual return on investment is $1.57 per kg.

A novel process for recovery of iron, titanium, and vanadium from titanomagnetite concentrates: NaOH molten salt roasting and water leaching processes

A novel process for recovering iron, titanium, and vanadium from titanomagnetite concentrates has been developed. In the present paper, the treatment of rich titanium–vanadium slag by NaOH molten salt roasting and water leaching processes is investigated. In the NaOH molten salt roasting process, the metallic iron is oxidized into ferriferous oxide, MgTi2O5 is converted to NaCl-type structure of Na2TiO3, and M3O5 (M=Ti, Mg, Fe) is converted to α-NaFeO2-type structure of NaMO2, respectively. Roasting temperature and NaOH–slag mass ratio played a considerable role in the conversion of titanium in the rich titanium–vanadium slag during the NaOH molten salt roasting process. Roasting at 500°C for 60min and a 1:1 NaOH–slag mass ratio produces 96.3% titanium conversion. In the water leaching process, the Na+ was exchanged with H+, Na2TiO3 is converted to undefined structure of H2TiO3, and NaMO2 is converted to α-NaFeO2-type structure of HMO2. Under the optimal conditions, 87.3% of the sodium, 42.3% of the silicon, 43.2% of the aluminum, 22.8% of the manganese, and 96.6% of the vanadium are leached out.

A novel process for recovery and refining of l-lactic acid from fermentation broth

This paper introduces a novel process for recovery and refining of l-lactic acid from a fermentation broth. The use of a solvent extraction step, in the novel approach, has significant impacts on the following centrifugal short-path distillation conditions (operating pressure, evaporator temperature and feed flow rate). As the conditions were varied, the l-lactic acid purity and yield in the distillate were monitored. For the purpose of comparison, a series of experiments were also carried out using the existing purification process. The results showed that both of the two processes can obtain l-lactic acid with a high purity around 91.3%, while the yield obtained using the novel process reached 61.73%, which was about 20.43% higher than that using the existing process. Additionally, multiple-pass distillation observed special attention by improving the yield up to 74.63%.

A novel process for recovery of fermentation-derived succinic acid

A novel approach to recover succinic acid from fermentation broth via acidification and esterification in ethanol is presented. Acid salts from fermentation are placed in ethanol along with a slight stoichiometric excess of sulfuric acid. Simultaneous acidification and esterification take place, with the inorganic sulfate salt formed precipitating out of the ethanol solution. The succinate is recovered as a solution of free succinic acid, monoethyl succinate, and diethyl succinate in ethanol, a mixture suitable for further esterification via reactive distillation. Recoveries of succinate species in excess of 95% were obtained for both model succinate salt solutions and for actual fermentation broth mixtures.

A novel process for recovery of tungsten and vanadium from a leach solution of tungsten alloy scrap

A process is developed in this study to recover tungsten and vanadium from a sodium tungstate solution containing 95 g/l WO 3, 0.175 g/l V and some impurities. The solution is produced by roasting a tungsten alloy scrap and subsequently dissolving it in an alkali solution. The process to recover tungsten and vanadium involves three steps: purification and separation of vanadium from tungsten, recovery of vanadium, recovery of tungsten. For the recovery of vanadium, MgCl 2 and ammonia solution are used in the purification step to precipitate the impurities and the vanadate. A small amount of acetic acid solution is then used to selectively dissolve the vanadium from the mixed residue and leave the impurities in the residue. Finally, NH 4VO 3 is precipitated by adding NH 4OH to the solution, to achieve a vanadium recovery of 88.28%. For the recovery of tungsten, the sodium salt is converted to calcium salt after purification of the sodium tungstate solution. The CaWO 4 is then converted to H 2WO 4 using a HCl solution, followed by dissolving in NH 4OH solution and crystallization of APT. A tungsten recovery of over 85% is obtained. The purity of both the final tungsten and vanadium products has met the standard specifications.

Membrane aromatic recovery system (MARS): lab bench to industrial pilot scale

This article describes a novel process for recovery of aromatic amines and phenolic compounds form wastewaters, the membrane aromatic recovery aromatic system (MARS). Laboratory work on wastewaters containing aniline and phenol will be presented, including data demonstrating removal and recovery of each chemical in a sufficiently pure form to allow recycling into a chemical production process. This article also describes successful scale-up and operation of the process through pilot trials at Solutia, UK. Process economics are discussed and data showing the potential for application of the process to a wide range of organic chemicals are presented.

A novel process for recovery of phenol from alkaline wastewater: laboratory study and predesign cost estimate

A novel process for recovery of phenol from alkaline wastewater has been demonstrated at laboratory scale. The process is based on the polymer‐supported phase‐transfer‐catalyzed reaction of alkaline phenols with benzoyl chloride dissolved in toluene. The reaction conducted in a triphase system at room temperature generates phenyl benzoate, which is subsequently recovered as the product. Phosphonium ion immobilized on chloromethyl polystyrene crosslinked with divinylbenzene was used as the catalyst. Laboratory experiments were conducted in a batch slurry reactor and a fixed‐bed reactor to assess the suitability of a particular reactor type to practical applications. An aqueous phase to organic phase volume ratio of 1:2 was found to be suitable. The slurry reactor was found to be more attractive for the reaction. Based on the result of experiments in batch slurry reactors and other processing steps, a conceptual flow scheme was proposed for the process, and a predesign cost estimate was made. As such, the treatment cost of the proposed process is higher than that of the usual solvent extraction process, but the capital cost is comparable. However, the cost of the recovered phenyl benzoate will more than offset the higher treatment cost. This is reflected in a payback period of 1.5 years for the proposed process as compared to 2.5 years for the typical solvent extraction process. For industrial applications, a pilot‐plant study needs to be performed for a detailed cost analysis.