Molten salt oxidation of organic hazardous waste with high salt content

Abstract

Organic hazardous waste often contains some salt, owing to the widespread use of alkali salts during industrial manufacturing processes. These salts cause complications during the treatment of this type of waste. Molten salt oxidation is a flameless, robust thermal process, with inherent capability of destroying the organic constituents of wastes, while retaining the inorganic ingredients in the molten salt. In the present study, molten salt oxidation is employed for treating a typical organic hazardous waste with a high content of alkali salts. The hazardous waste derives from the production of thiotriazinone. Molten salt oxidation experiments have been conducted using a lab-scale molten salt oxidation reactor, and the emissions of CO, NO, SO, HCl and dioxins are studied. Impacts are investigated from the composition of the molten salts, the types of feeding tube, the temperature of molten carbonates and the air factor. Results show that the waste can be oxidised effectively in a molten salt bath. Temperature of molten carbonates plays the most important role. With the temperature rising from 600 °C to 750 °C, the oxidation efficiency increases from 91.1% to 98.3%. Compared with the temperature, air factor has but a minor effect, as well as the composition of the molten salts and the type of feeding tube. The molten carbonates retain chlorine with an efficiency higher than 99.9% and the emissions of dioxins are below 8 pg TEQ g sample. The present study shows that molten salt oxidation is a promising alternative for the disposal of organic hazardous wastes containing a high salt content.

Retracted: The Effect of Air on the Oxidation Decomposition of Cationic Exchange Resins in a Ternary Li2CO3−Na2CO3−K2CO3 Molten‐Salt System

“…[12,13] Compared to the other technology, such as incineration and curing, MSO technology has relatively low operating temperature and captures off-gas released from the MSO process by molten salt and thus simplify the treatment system of tail-gas. [6,[13][14][15][16][17] Lawrence Livermore National Laboratory (LLNL) explored the oxidation decomposition of shredded booties by MSO technology and the result was quite promising. The concentrations of total hydrocarbon (THC) and CO in the off-gas were less than 5.0 ppm and 40 ppm, respectively.…”

“…[7,[26][27][28] This could lead to organic hazardous waste being destroyed more effectively in molten salt. [6] In addition to the above substances, the MSO method is suitable for the treatment of other materials, such as chlorinated organics (poly-(vinyl chloride), [29] trichlorobenzene [30,31] ), nitrobenzene and its derivatives. [32,33] The MSO treatment process of waste has been extensively investigated by some researchers.…”

Study on the transformation of organic sulfur in cationic exchange resins in a ternary Li2CO3–Na2CO3–K2CO3 molten salt system

“…8, the binding energy value of S3 at 169.2 eV was related to the values for benzenesulfonic acid (C 6 H 5 SO 3 H), and S2 was associated with diphenyl sulfone (C 6 H 5 ) 2 SO 2 . 17,18 The binding energy values of S1 at 164.2 eV corresponded to the values for the phenyl sulfide polymer (C 6 H 5 S) n .…”

“…Apart from the absorption of volatile nuclides, the off-gas released from the MSO process can be captured by molten salt, thus simplifying the treatment system of tail-gas. [13][14][15][16][17] Flandinet et al 18 applied molten KOH-NaOH eutectic melts for the disposal of plastic and found that molten hydroxides, owing to their high basicity, dissolved and trapped many gases, such as halogens or carbon monoxide and dioxide. In the meantime, alkali metal hydroxide (LiOH, NaOH, and KOH) can also be used to capture acidic gases, such as H 2 S. 19,20 Because sulfur-containing gases cause serious environmental pollution, molten salt significantly affects the treatment of sulfur, including solid waste.…”

The heavy metal leaching property and cementitious material preparation by treating municipal solid waste incineration fly ash through the molten salt process

“…As a heat transfer medium, molten salt could enhance heat transfer. Therefore, the molten salt method provides a new way to dispose of pyrolytic organic solid wastes (Lin et al, 2016(Lin et al, , 2018. However, to directly treat of FA with the molten salt method has not been reported in recent years.…”