Loss on Ignition test method and procedures for limestone sample

Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3).

Limestone is composed principally of calcium carbonate, which when heated at elevated temperatures decomposes to calcium oxide and carbon dioxide.

    CaCO_{3     +         Heat     =}   CaO + CO₂

Loss on Ignition

  When limestone is heated at elevated temperatures, carbon is lost to the air as carbon dioxide (CO₂) leaving behind the calcium oxide component.

Below is the determination procedures 

Equipment and Apparatus

1.Spatula

2.Analytical Balance

3. Glass weighing Bottle

4. Platinum crucible

5. A murfle Furnance

6. Agate Morter

Preparation of Sample for Analysis

1.11   Procedure: Sample randomly, small portions from the bulk of the material to reach about 1000g; dry if wet in the oven at 110^OC for 1 hour.       Mix together the dry sample on a graph paper, spread evenly and scoop      small quantities at a time unto another paper using a clean spatula,      again mix and spread as          before. Finally scoop about 5g from the entire spread surface into an   agate mortar, pulverize, and transfer into a weighing bottle; dry in the oven at        110^OC for 1 hour, and cool in the desiccator to room           temperature.      

Test Procedure:  Weigh a clean platinum crucible with a lid, note the weight;  transfer 1.0 g of the ground sample into it, cover with the lid and weigh again; note the total weight. Transfer the charged crucible into a muffle furnace, raise furnace temperature from 0 to 1000 ^OC and ignite for 1 hour, cool in the desiccator to room temperature and weigh to determine the loss in weight.

Loss on Ignition (CO₂)   =    Change in weight      x 100%

                          

                                              Sample Weight

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