Eliminating Dust In Handling Cement

Press, Volume XCIX, Issue 29189, 27 April 1960, Page 22

Eliminating Dust In Handling Cement

A pneumatic handling system that entirely eliminates thv dust nuisance encountered when cement is handled has been installed at Hornby. This is the first rail pneumatic bulk handling plant in New Zealand.

A special railway waggon for carrying pulverised materials such as cement in bulk was built at the Addington Railway Workshops to carry the cement from the Milburn Lime and Cement Company’s works at Burnside, Otago, to Hornby. The aim of the pneumatic plant is to provide a quick, clean and economic method of handling cement, from cement factory to the silo of the user.

Until recently all cement had to be mechanically scraped out of open railway waggons and carried by a bucket elevator into the silo. In the new scheme the cement is untouched by hand and unseen from the time the cement is weighed out of the Milbum Company’s works at Bumside until it is made into

concrete products at Vibrapae Blocks, Ltd., plant at Hornby. Specially sealed tanken. consisting o2 two double pressure tanks with one unit on each end of a UE waggon are used to load the cement Each tank unit can carry 12 tons of cement so that 24 tons can be carried by the tankers. The tanks are filled at the cement works, the lids bolted down and the waggons sent by rail.

When the cement tankers arrive at Hornby hoses are connected with the loaded tanker, the cement delivery pipe running to the elevated silo and to the air supply. The design of the tank allows the air to enter beneath the cement which is then aerated and becomes fluid. When all the cement in the tank is rendered fluid the valves are opened and the fluid air-cement mixture is blown into the pipelines and into the silo.

The rate of discharge is approximately one ton a minute, each tank being discharged in six minutes. As considerable quantities of compressed air are required to aerate the cement and transport it along the delivery pipes, a large air compressor has been installed.

As cement sets in the presence of water special devices have been installed to ensure that the compressed air is completely free from oil and moisture.

The heavy particles of cement settle out as the mixture of air and cement enters the silo. A filter is provided on the top of the silo to catch and return the finer particles of cement, and yet allow the spent compressed air to escape. The Vibrapae Blocks Ltd. plant at Hornby uses large quantities of cement in its concrete masonry work and the elevated silo at the plant is capable of holding 70 tons of cement.