By understanding the key slurry properties in the laboratory, we are able to more accurately understand how the slurry will behave under the expected plant conditions
Ausenco engineer conducts rheological tests
In this interview with Ausenco’s Senior Mining Engineer, Charleston Dias, we discuss the services our rheology lab in Brazil provides for our pipeline clients and how the information from the lab results leads to effective pipeline design and the appropriate selection of pipes, pumps and other equipment.
Why is rheological characterization important for slurry pipeline projects?
Understanding and studying the flow of complex liquids such as the solid/liquid properties of a slurry, enable us to quantitatively evaluate pumpability and plugging risks during a pipeline shutdown or restart. Additionally, we can easily test rheology modifiers to optimize safe and more efficient pumping.
Each slurry and its behavior are different. By understanding the key slurry properties in the laboratory, we are able to more accurately understand how the slurry will behave under the expected plant conditions. This information is vital to correctly design the pipeline and choose the appropriate pumps, pipes, and other equipment, thus potentially saving costs in the long run.
Where do you conduct your rheological work?
Ausenco rheology lab in Brazil
Our rheological work is conducted in our Brazilian laboratory, which has been in operation for the last 13 years. We have characterized hundreds of slurry samples for our clients’ pipeline projects. The most important factor when performing mineral pulp testing is result accuracy; since the results provide critical data needed to define hydraulic parameters to determine appropriate specifications for pipe and pump. To minimize the margin of error our state-of-the-art laboratories and experienced laboratory technicians follow rigorous quality control standards. We strive to ensure the highest levels of quality and accuracy for all sample testing. Our lead specialist has over 25 years of experience as a mineral technologist developing several applications in solid filtering.
Does Ausenco do lab tests instead of hydraulic loop tests?
Our laboratory in Brazil does not normally need loop testing. Instead, we test slurry pumping and corrosion conditions by evaluating the following on a bench scale level in our laboratory:
Effect of shear on slurry rheology
Viscosity and yield stress
Slurry oxygen level
pH variation and corrosion rate
Additional special slurry parameters
Agitation tests are carried out in an air-tight reactor under controlled temperature, oxygen and pH conditions in order to simulate actual pipeline conditions. This methodology provides more precise data than a pipe loop test. Pipe loop tests also generally require scale-up to a larger pipe size, so that even if a test loop program is carried out, there still is the scale-up that can generate error.
Why dismiss loop tests?
Loop testing proves to be costly for clients, generally requires a very large sample and has inherent difficulties in providing the needed data. The larger sample may require a pilot or operating plant to produce. We also believe that loop tests do not accurately simulate ‘real world’ conditions. For example, multiple pass loop tests contact a centrifugal pump many times during slurry recirculation through the loop. This process that can grind the particles to smaller size, change particle shapes and elevate the slurry temperature. Once the tests have been performed, there is then the challenge of scaling the loop test results on a smaller pipe(s) to the actual project pipeline diameter.
What sample size is required for laboratory testing?