Caustic Soda Solidification

Date : Feb 2013 - Mar 2013

Composition KNo3 = 53% NaNo2 = 40% NaNo3 = 07% Working temperature = 160 ~ 500°C Material used = Heat resistant steel type 15 Mo3 under 490°C. Cr Ni type steal under 550°C. Acceptable Level of Impurities S = 0.025% maximum. At higher level S reacts with Ni elements. Ni + S = NiS Cl Content = 0.1% At higher level there is a danger of corrosion tension stress hair crakes in stainless steal materials. Thermally satiable upto 480 °C. Slow decay range = 350 ~ 480 °C. At higher temperature NaNo2 converts as; 3NaNo2 = NaNo3 +Na2O+ 2NO At higher level of NaNo3 & Na2o, MP of salt rises. Allowable Na2o content = 1.55% maximum. Reaction with O2 NaNo2 + O2 oxides to NaNo3 (MP will rise). Reacts with CU & Ag (Should not be used for transport and sampling pot). Mild Steal (Reacts above 500°C causing an exothermic react), Should prevent MS getting in contact with salt melt having a temperature above 450°C. Pure NI & Slag free Alloys Do not react even at temperature greater than 600°C. Corrosion rate is very low. Reaction with Organic Compounds Organic compounds may flare up or explode when in contact with salt melt due to No2, & No3 contents. (Paper, wood, lignite, coke) etc reacts through violent (combustion) reaction. Acceptance level = 0.2% Effect = Rise the M.P. Origin of CO2 = N2 used for blanketing. Corrective action = Salt Renewal Effect of NaoH Acceptance level = 2.0 % Effect = Rise the M.P. Corrective action = Salt Renewal Physical Characteristics Sp. Heat = 0.34 Kcal/ kg°C Heat of fusion = 20 Kcal/ kg Cubical expansion coefficient = 1.13x10-4/°C (A minor contraction occurres on crystallization) M.P = 142°C. Salt rests must not be disposed off on a garbage dump as it contains NO2___H2O poisoning. In case of leakage, collect the salt in steal drum when solidified Smaller Amount may be flushed away with water (plenty).