Australian
Screen

Teacher’s notes

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This silent black-and-white clip from a 1920s industrial documentary shows stages in the process of refining limestone slurry into clinker and then made into cement at the Portland Cement Works in New South Wales. Intertitles describe each process. The liquid slurry is turned by huge paddles in vats and then moved to a large rotary kiln, which is viewed from different vantage points including a glimpse into the furnace. Finally, the camera follows men walking beside the tube mill, which is grinding the clinker to produce cement.

Educational value points

• The Portland Cement Works are shown at a time of increased mechanisation in the Australian cement-making industry, following the expansion of reinforced concrete construction after 1900 and the cessation of cement importation during the First World War. In the 1920s improved Australian production standards were introduced. Technical development led to larger rotary kilns and new multi-compartment tube mills such as the one seen here.

• This clip describes the process of manufacturing cement. Crushed limestone makes up 75 per cent of the mixture seen in the mixing tanks. Clay and water make up the remaining 25 per cent, forming a slurry, which is piped to the rotary kiln. In the kiln intense heat dries the slurry, fusing the solid material to form dry clinker. The rubble-like clinker is then conveyed to the tube mill where it is ground and gypsum is added to form fine cement powder.

• The clip focuses on the impressive scale and functions of the rotary kiln, particularly its long metal cylinder, which is inclined so that the rolling mix of slurry slowly moves along its length. It is perhaps 2-3 m in diameter and between 30 m and 50 m long. Its external cogged rings engage with the gears that rotate it. Through a window, a man monitors powdered coal, which is blown in through the centre of the tube as it creates intensely hot gases to form the clinker.

• A variety of camera angles and positions has been used by the filmmaker to impress the viewer with the scale of the machinery being used at the plant. These include panning shots from above of mixing tanks and from below of the length of the tube mill. Its scale is indicated by the men who walk alongside. A giant cog on the rotary kiln is seen in medium shot with the figure of a man providing perspective. A close-up shows giant scoops collecting the slurry.

• Portland in NSW may have been named after Portland cement, the type of cement being made here. The process was developed in England in the early 19th century. The NSW cement works was the site of one of Australia’s most successful long-term lime-quarrying and cement-manufacturing enterprises. Between 1902 and 1995 the site was responsible for the large-scale production of quality cement, consistently using the latest technology.