MILLING PROJECT SUMMARIES The following summaries relate to milling research undertaken by Queensland University of Technology with funding from SRA. Updates were presented at the recent Regional Milling Research Seminars.
Investigations to mitigate the effects of juice degradation in factory evaporators on sugar recovery and quality, corrosion, and effluent organic loading
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ucrose degradation reactions during juice evaporation cause a direct reduction in sugar yield and revenue. The associated degradation of monosaccharides and other components produces acidic compounds which cause corrosion of pipework, tube plates etc. The aim of the project was to provide a better understanding of the causes of sucrose degradation and acid formation in factory evaporators and their effects on sugar recovery, sugar quality, corrosion and effluent loadings, and to develop strategies to mitigate these issues. Anecdotally, improving the quality of juice has been shown to minimise sucrose degradation but detailed attribution to specific impurity types (phenolics, proteins, sulphurous compounds, etc) has not been determined in factory juices. Composite sampling and analyses of juices, syrup, condensates and vents across the evaporator station were undertaken at Isis, Invicta, Condong, Pioneer and Rocky Point mills over the 2018, 2019 and 2020 seasons.
Cane Matters / Autumn 2022
A test program has been conducted as part of a PhD study to examine the pathways of sucrose and monosaccharide degradation by boiling synthetic solutions as well as factory juices in pilot plant evaporator equipment.
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These studies have investigated the impacts of pH and individual juice components on the degradation rates and shown that there is substantial interaction in the effects of the individual juice components.
PhD student Chalani Marasinghege and QUT's Darryn Rackemann monitor operation of the pilot evaporator rig at Rocky Point Mill.
The PhD student, Ms Chalani Marasinghege, presented these results at the 2022 Australian Society of Sugar Cane Technologists conference in Mackay and was rewarded with the Denis Foster Chemistry/Chemical Engineering Award for her paper.
Various mitigation strategies were also tested in the pilot evaporator. Mitigation strategies focus on minimising the sucrose loss from occurring through equipment or process design or dealing with the acidic components produced.
