Oxidation process, molten nitrate salt

Molten Nitrate Salt Oxidation Process (10). The reaction of UO2 with molten nitrate salts to form uranates that are sub-sequently reduced to effect a separation of the uranium is being evaluated. The actinide behavior and uranate composition in equimolar sodium-potassium nitrate is being studied to determine the uranate stability and forecasting of cation behavior in subsequent process steps. 

Hot corrosion is designated as the accelerated attack of metals and ceramics in oxidizing environments by the presence of a thin molten salt film, for example, a fused sulfate, carbonate, chloride, or nitrate. In many high-temperature processes, molten salts are present either in partially molten ashes, as deposits on boiler tubes from conventionally fired plants such as waste fired boilers (chlorides, sulfates), as a single salt deposits on gas turbines (Na2S04), or as the electrolytes in molten carbonate fuel cells [(Li,K)2C03]. 

The Harris process removes arsenic, antimony and tin by oxidation with sodium nitrate and reaction with sodium hydroxide to form sodium arsenite, sodium antimonite and sodium stannate, which form a molten salt solution in excess sodium hydroxide. Sodium chloride can be added to extend the solvent (Paschen and Winterhagen, 1968). 

The removal of small quantities of arsenic from metals and ores is a commercial problem which may be mentioned at this point. The Harris process of softening lead,6 used in several refineries, is based on the principle that such impurities as arsenic, antimony and tin may easily be oxidised and in the presence of certain alkali salts can he converted into arsenates, antimonates and stannates. Certain fluxes, such as sodium nitrate, sodium hydroxide, sodium chloride or lead oxide, are added to the molten lead, the presence of an oxidising agent and an alkali salt being essential. The alkaline slag obtained is fused 7 and... 

The cheapest type of nitrate-to-oxide conversion process, based upon thermal denitration, has been shown in Fig. 9.3. This can be carried out in a simple batch type of pot denitrator or in more elegant continuous plant for larger scale production. If a little iron impurity is introduced, the molten salt electrolysis stage which follows allows an opportunity for purification again before the metal powder is produced. 

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