Molten salt oxidation
Encyclopedia
Molten salt oxidation is a non-flame, thermal process that destroys all organic materials while simultaneously retaining inorganic and hazardous components in the melt. It is used as either hazardous waste treatment
(with air) or energy harvesting similar to coal and wood gasification
(with steam).
The molten salt of choice has been sodium carbonate
(m.p 851°C), but other salts can be used. Sulfur, halogens, phosphorus and similar volatile pollutants are oxidized and retained in the melt. Most organic carbon content leaves as relatively pure CO//H2/H2O gas (depending on the feed conditions, whether steam or air is used), and the effluent only requires a cold trap and a mild aqueous wash (except mercury containing wastes). It has been used for safe biological and chemical weapons destruction, and processing waste such as scrap tires where direct incineration/effluent treatment is difficult.
The major downside of the process compared to direct incineration is the eventual saturation of the melt by contaminants, and needing reprocessing/replacement.
Waste treatment
Waste treatment refers to the activities required to ensure that waste has the least practicable impact on the environment. In many countries various forms of waste treatment are required by law.-Solid waste treatment:...
(with air) or energy harvesting similar to coal and wood gasification
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...
(with steam).
The molten salt of choice has been sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
(m.p 851°C), but other salts can be used. Sulfur, halogens, phosphorus and similar volatile pollutants are oxidized and retained in the melt. Most organic carbon content leaves as relatively pure CO//H2/H2O gas (depending on the feed conditions, whether steam or air is used), and the effluent only requires a cold trap and a mild aqueous wash (except mercury containing wastes). It has been used for safe biological and chemical weapons destruction, and processing waste such as scrap tires where direct incineration/effluent treatment is difficult.
The major downside of the process compared to direct incineration is the eventual saturation of the melt by contaminants, and needing reprocessing/replacement.
See also
- Recovery boilerRecovery boilerRecovery boiler is the part of Kraft process of pulping where chemicals for white liquor are recovered and reformed from black liquor, which contains lignin from previously processed wood. The black liquor is burned, generating heat, which is usually used in the process or in making electricity,...
- a technology with similar issues used in Kraft processKraft processThe kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
chemical pulping of paper, though temperatures <500°C