Increasing storage safety after mineral extraction
When companies extract minerals from the ground, they are generally left with a liquid slurry made of fine particles and water - "tailings". This creates the problem of storage. Excess water in the tailings can lead to a disaster. For the tailings to be safely stored, the water needs to go.
Scientists from Australia's national science research agency, CSIRO, are investigating methods of more efficiently extracting the water, and are using Windmill software to measure the expulsion of liquid under different conditions.
Injecting polymer additives can accelerate the water recycling. Led by Allan Costine, the team used a clay suspension to study the effect of different proportions of polymers. They pumped the clay suspension and polymer solution into a mixing vessel. They tested two types of mixer - a chaotic or topological mixer and a pitched blade turbine mixer - to produce flocculated solids with vastly different dewatering properties.
When a stable mixing state was reached, the scientists collected a sample of the conditioned suspension and ran the Windmill data logging software to record the mass of water expelled every minute. They continued to log data for 24 hours, with most of the recoverable water collected in the first two hours. Comparing different polymer solutions and mixing methods, the research team highlighted methods to markedly improve water recovery - thus protecting the environment, improving safety and reducing costs
Costine, Allan; Fawell, Phillip; Chryss, Andrew; Dahl, Stuart; Bellwood, John. Development of Test Procedures Based on Chaotic Advection for Assessing Polymer Performance in High-Solids Tailings Applications. Processes. 2020; 8(6):Article 731. https://doi.org/10.3390/pr8060731