No_1_May_and_June__1951 — Page 30

Another view of the tunnel kiln, looking towards the drying

bricks are allowed to remain until sufficiently dry to be able to pass through the high temperature of the kiln without danger of dis- tortion through excessive shrink-

age.

At The Keen Sang Brickworks there are a number of kilus; the original Hoffman chamber kiln which was the one built in 1931, and the tunnel kiln which was built by Mr. Lee Ching immediately after the reoccupation of the Colony. There are also several small kilus used for the production of the cheaper qualities of brick.

Rail-way from the clay pits to the mixing machine, definite proportions capable of pro- ducing the high quality brick in which the company specialises. This refined material is then hoisted above, and deposited into, the clay-mixing ma- chine where it is thoroughly ground and mixed with a carefully controlled amount of water and is extruded from this machine under pressure in the form of a continuous plastic bar from which the bricks are wire cut. These units are loaded from the machine on to steel platform trucks, which are first moved into a storage area where they are air-dried for a number of days. The trucks are then rolled into long tunnels, which are heated by the ex- haust from the kilns, where the green

The Hoffman kiln contains 36 cham- bers or units, each with a capacity of 1000 cu. it. of brick. The overall dimensions of the kiln are, length 300', width 150' and height 12'. Ori- ginally this kiln was constructed to burn coal only, but the flues and pip- ing have recently been altered so as to allow for oil as an alternative. When

l is being used as the fuel, high powered blowers are used to distribute heated air through the chambers, but

when coal is being used huge extrac- for fans at the discharge end are put into action which draw the heat

through the chambers- In both cases, as has already been mentioned, this heated air is exhausted into the drying tunnels. This kiln when in operation is fully loaded with cars of bricks and then sealed. The fires are then started up and the heat gradually increased to the maximum temperature of 1100 deg. Centigrade, maintained at that level for 24 hours and the fire is then allow- ed to die down. When the bricks are cool enough the kiln is unsealed and the bricks removed for grading and storing.

The Tunnel kiln is of the continuous production type in which the cars load- ed with brick move slowly and con- tinuously through zones of gradually increasing heat until they are subjected to the maximum temperature of 1400 degs. Centigrade, and then through gradually decreasing heat zones. By the time they reach the discharging end of the kiln they are cooled down sufficiently so that their removal into

A view of the Hoffman kiln,

The battery of drying kilns,

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