New era of bagged premix products - Contractor

Cemix Drimix is installing a new plant incorporating the latest European equipment to supply the New Zealand market with a range of precisely formulated drymix products.

The fully automated plant in Onehunga/Penrose which will have the capacity to produce 15-20 tonnes of finished bagged products an hour, or 48,000 tonnes a year on one shift.

The plant handles dry powder material without using screw conveyors or air slides. Instead, it incorporates the patented fluidization technology from Raute Precision Oy from Finland, which makes powders (sand and cement) flow like liquid, enabling the use of double flap butterfly valves for accurate and high-speed dosing, Cemix Drimix principal Geoffrey Clark said.

The computer-controlled, compact plant has a footprint of 8 by 8 metres and a height of 33m, yet has the unparalleled capability to produce products with up to 17 different ingredients.

The process starts with the drying of sands and aggregate materials by a fluidized bed dryer from Holland which is completely sealed and recycles hot air, thus reducing the use of natural gas. The plant was granted building consents because of its extremely low emissions.

The bucket elevator was designed and built in New Zealand, the packaging line was designed and built in Australia, the compressors are from the USA, the material lifting technology from Sweden and the plant was fabricated in New Zealand from Raute drawings. The high-tech mixer is of Norwegian design, equipped with high-speed choppers that ensure homogeneity of products, even when there is a high content of powder chemicals and pigments.

The bagging line is fully automated with automatic valve bag placers and a robotic palletiser. Finished product will be packed and palletised into 40, 25 or 10kg bags or bulk bags palletised and stretch-wrapped to keep the product waterproof and fresh.

Project Manager Bhav Dhillon has had several years of experience in the drymix industry, particularly in setting Raute plants throughout the world. He said that, until now, there has been little control over what happens on a New Zealand building site. ‘Concrete blocks are made to fairly rigid specifications, yet builders mix, concrete and mortar are dumped on site with shovels.’

He says future legislation will tighten up on these unsafe practices and Cemix’s new plant will offer consistency, low cost products, enhanced product performance and a wider range of products, although it will initially supply dry concrete, quicksetting concrete, mortar mix and grout.

‘ Other suppliers say sand is sand, but we split it into three fractions and recombine them into whichever proportion is appropriate. We have a fully functional lab on site – one of the best in New Zealand for testing concrete and mortars, and it is open to our customers.

‘ All raw materials are tested prior to mix and also afterwards for quality under a sampling regime – this degree of sophistication is not yet available in Australia or the USA. The initial capacity is for 17 silos of varying sizes which will have the capability to weigh and mix 17 different raw materials.

‘ The mixer can consistently mix colour as the plant has shearmakers and there is a very high shear in powder mix. It also has a lightweight concrete and perlite plaster. We will also be producing polypropylene fibre reinforced concrete and in time will be supplying oxides for colouring and white cement as as well as a wide range of sands, concretes, mortars, grouts, self-levelling flooring products, plasters etc.

‘ The products will be distributed throughout New Zealand by selected hardware stores and we aim to properly support the end user with active demonstrations and point-of-sale support.’

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