Lime Production in Sri Lanka - Central Province, Sri Lanka

Lime Production

Location

Mathale district central province Sri Lanka

Production

Traditional techniques are still using to produce lime in Sri Lanka.Klins using dolomite limestone had used for the production. The kiln consist of a crucible shaped pit built in a chamber of muds and bricks. The pit is about 3’-4’ in diameter and 5’-6’ in depth ending in a curved bottom where a grating of steel rods prevents the passage of unburnt raw materials.

Kiln Arrangement

The first load that goes into the pit consists of heavy logs of timber. The timber logs used are 2’ to 3’ in length and may vary from 4”-12” in diameter. The timber logs are stacked at the bottom of pit and over these a few baskets of 1”-2” sized dolomite aggregate are placed. This is carried on till the pit is about three quarter full, the top layer consisting of logs of timber. One complete feed of the kiln may consist of 8-10 cubic yards of firewood and approximately 50 cu.ft of aggregate.

The feed is alight by kerosene soaked rags as in the limestone kiln. The magnesium carbonate breaks down at a temperature of about 480oC in the following manner.

When the temperature rises further to about 900oC, the Calcium Carbonate dissociates as follows.

As the burning proceeds and the level of material in the kiln falls, more aggregate and firewood are added to keep the kiln burning for several days. This may be used either as batch or a continuous process depending upon the market for lime. As the burning proceeds the firewood is reduced ash and the dolomite aggregate is converted to oxides.

In this state the burnt aggregate may be made to fall through the grating by tapping it lightly using long handled hoes. The lumps and powder that fall through the grating may be removed through the tunnel to outside area of the chamber using the same long handled hoes .On cooling the under-burnt aggregate which may be made out by its appearance and feel is removed. The ash from the firewood has the consistency of a fine powder and is of a different, color from the lime. This fact is used in removing at least some of the ash from the mix.