RAS-1984 — Page 318

The process of making lime

The process of making lime is divided into four stages:

(1) Burning

(2) Slaking

(3) Sieving

(4) Bagging

The whole process of making lime takes about four days to complete.

Burning

For burning, a furnace, or kiln, is used. This is made of fire-resistant bricks,* and can be either round or square in shape. It is usually about three English feet in height, open to the air at the top, and covers about 100 square feet. A kiln can produce about 100 piculs at a firing.

For burning it is necessary first to mix together the ground shells and ground charcoal. Then this mixture is spread out carefully in thin layers on top of a layer of dried grass which covers the floor of the kiln. The floor of the kiln has an iron grate, or an iron plate with a network of holes, to facilitate the passage of air. Below the kiln is an air passage which passes to the engine room. Firing begins with setting fire to the dried grass on the floor of the kiln, then a diesel engine or motor in the engine room is started to force a stream of air along the air passage into the bottom of the kiln (previously this was done by using bellows worked by man power). In this fierce draught the fire lit in the dried grass spreads to the mixed together shells and charcoal. After the fire has burnt through the shells with its fierce power, it moves on to the next layer, and so, layer by layer, to the top of the kiln. The fire needs to burn right through to the top at full heat before the work is completed, and this takes about six hours.

Opening the kiln and scraping out the shell residue is done the following day after the kiln has cooled off.

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