Pump News

January 5, 2022

Characteristics to Slurries

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First off, everyone should know a little bit about what slurry is before trying to handle a slurry pump or work with slurry pumps of any kind. There are three main characteristics to slurries everywhere that you need to worry about, and those include:

• Viscosity
• Corrosivity
• Solids Content

At an observational level, viscosity describes how thick a slurry is, and you can measure viscosity by a fluid’s resistance to shear or flow. If the slurry has low viscosity, close to that of water a.k.a. a Newtonian fluid, it can flow through most systems as long as particulate matter stays suspended in the slurry mixture. In contrast, if the slurry has a high viscosity it could cause serious damage to your pump and other components if not properly treated or handled. It could even clog up piping, causing a dead-head situation, ruining your pumping system entirely! Ensure that you have applied the correct equipment when pumping a medium with a high viscosity.

Corrosivity is a loose term used to gauge how potentially corrosive, or damaging via chemical reactions, a slurry or other fluid could be to a pump or system it is moving through. If it has low corrosivity, you shouldn’t have to worry about whether or not the components in the slurry will damage your equipment. However, if it has high corrosivity, then you need to do more to protect your pumps from being damaged by those same chemicals. There are two types of corrosion: localized and general corrosion. Localized corrosion happens when one material corrodes at a rate much higher than other materials around it and leads to holes forming and eventually collapsing the whole system containing them (in this case your pump). General corrosion happens when all the materials corrode at the same rate and lead to a gradual buildup of corrosion. This can lead to holes as well but it is significantly harder to notice as the buildup happens over a long period of time (maybe even days or months depending). Schurco takes corrosion factors and corrosivity into consideration whenever selecting materials for a slurry pump application.

Finally, solids content specifies how much non-fluid material you will be pumping that is liquid vs solid within the slurry. There are some upper limits to concentrations of solids by volume that centrifugal slurry pumps can handle, and the actual values for concentration by weight and volume of any given slurry will help an application engineer
to specify the best possible pumping solution for your system. Particle sizes, both maximum and mean, play a major role in pump selection, and also have an impact upon whether or not a slurry may settle in a long pipeline.

Do you know what makes up a slurry? In its most basic definition, slurries are a mixture of fluid and solids. Slurries can be homogenous (think homogenized milk!) and heterogeneous (think a bowl of melted Rocky Road ice cream with all the extras just sitting or floating in the melted cream). These examples use dairy products as an analogy; however, most slurries pumped in mining and related industries involve a mixture of water (the fluid) and dirt, sand, or gravel (the solid).

There are two main categories of slurries, which are settling and non-settling slurries. As the name indicates, the non-settling slurry is rich in fine material/particles, and is often homogeneous in nature. A settling slurry is made up of larger and coarser particles. These settling slurries are harsher on pumps due to the larger and more abrasive solids that would be present.

When choosing a slurry pump for your job, it is crucial to consider all the factors you know about your slurry and best fit the pump for the job. There are many types of centrifugal pumps, but it is important that you consult with the pumping experts, like at Schurco Slurry Pumps, to get the best pump for your job today!