Bundaberg Sugar Millaquin Mill

Centrifugal machines installed at the mill.

New primary juice tank and pumps installed at the mill.

Sugarcane juice is heated in effets using a combination of vacuum and steam to produce sugar.

The Millaquin mill is undergoing a $40m upgrade to modernise its facilities.

At the Millaquin mill, sugarcane is crushed and processed to produce both raw and refined sugar.

Bundaberg Sugar’s Millaquin sugar mill is situated near the Burnett River in Bundaberg, Queensland, Australia. The mill was originally built in 1882 and includes a large refinery.

Sugarcane produced in the nearby areas is crushed and processed to produce raw and refined sugar at the facility.

Millaquin sugar mill upgrade

The Millaquin mill is currently undergoing a $40m upgrade to modernise facilities. The upgrade programme began in 2008, and will install a new vacuum pan and a cane juice tank. Centrifugal machines and a heater will also be installed. The three steam engines currently operating at the plant will be replaced with electric drives.

The mill’s landmark 62m chimney stack will be replaced by a more efficient and environmentally friendly 35m chimney. A new power generator is also part of the upgrade programme. The generator will provide surplus power, which can be fed back to the electricity grid and power 300 local homes.

As part of the upgrade, Bundaberg Sugar has already spent $8m modernising the boilers and increasing their capacity. Another $14m will be spent in 2010 to modernise additional facilities.

During 2011-2012, new conveyor belts for sugar and bagasse pulp will be installed. Diesel back-up generators and an additional juice pump will also be fitted during this period.

The upgrade programme will help to reduce carbon emissions at the facility. As the boilers will be electrically driven, the use of coal will therefore be reduced, resulting in the reduction of carbon emissions to 20% below current permitted levels.

The government is giving $220,000 to Bundaberg Sugar for the upgrade programme. The funds will be used to install a near infrared spectroscopic analysis system in the facility. The new system will help to examine the attributes of sugarcane, and the collected data used to improve farming, harvesting and milling operations.

Sugar cane processing

After the sugar cane is harvested it is cut into 20cm-long strips called billets. These billets are taken to the mill and crushed using large rollers. This process produces raw sugarcane juice and a watery fibre residue known as bagasse.

The raw juice is then heated to 75°C to melt any starch present. This heated solution is then incubated for about 30 minutes. A lime solution is added to the juice to change its PH and heated once again to 100°C. The juice formed is called the secondary juice, which is exposed to atmosphere. This allows gases present in the juice to escape.

The juice is once again allowed to settle and a small amount of binding agent called flocculant is added. This allows any impurities present in the juice to separate and settle at the bottom of the tank.

The clear juice, known as evaporator supply juice, is removed from the top of the tank and sent through large upright cylinders called effets. The impurities from the juice are collected from the bottom of the tank and placed in large rotating drums to separate the sugar. A vacuum is used to remove any impurities and this remaining juice is added to the juice collected from the top.

The juice obtained is heated in the effets using a combination of vacuum and steam. This is done to avoid burning of the sugar in the juice. As the juice is heated, steam is released from the effets and the sugar starts to concentrate. The juice passes through four to five effets to produce a syrup which is stored in a tank.

The syrup is heated and reheated to extract all sugar present. Three types of sugar are produced during this process: A-sugar, B-sugar and C-sugar. These sugars can be further processed in refineries to produce different types of sugar such as table sugar, white sugar and coffee crystals.

Millaquin contractors

During 2008-9, local construction and engineering company Rabmint completed the installation of the new stack and new crystalliser coils at Millaquin sugar mill. The company also installed a new pan and other essential pipe work.