Slurry Stirrer – Features and Options
Whether stored in tanks, open lagoons or in underground reception pits, slurry will require regular mixing with a slurry stirrer. Here we take a look at why this is necessary, the main features of slurry stirrers and the range of options available from slurry equipment supplier Tramspread, based in Stowmarket, Suffolk.
Why Does Slurry Need Stirring?
There are a number of reasons why it is necessary to stir slurry held in a pit or lagoon.
By far the most important reason is to enable optimum pumping performance. Although many slurry pumps include a built in cutter, but performance will be reduced if the slurry contains very large lumps or clots of solid material. An uneven consistency can be caused by the presence of solids within the slurry itself (e.g. undigested food, plant fibres), or by the formation of a crust over the top of the slurry, which is common in open air silos or lagoons. Using a slurry mixer helps to break up these solids and maintain a more homogenous consistency which enables a pump to work at optimal efficiency.
A second reason is to distribute nutrients. Since the purpose of slurry spreading is to provide fertilisation, it is advantageous if nutrients are dispersed evenly throughout the mixture, resulting in more uniform fertilisation.
One other advantage of ensuring that slurry is well mixed prior to pumping is that it is much easier to completely empty a slurry store containing a homogeneous mixture compared to one containing a high level of non-homogenised solids which are likely to be left behind as sediment.
Features of Slurry Stirrers
A slurry stirrer is comprised of three main components: a shaft, a mixing blade and a power source.
Shaft – The shaft connects the power source to the mixing blade and can be of variable length depending on the distance from the power source to the mixing point. The length and design of the shaft can be varied to cope with different types of slurry store. For very large lagoons, the shaft may need to be several metres in length and supported with struts or other structures, plus some system to help the mixer to be inserted and retracted easily, such as telescopic or folding arrangements.
Mixing Blade – At the end of the shaft is a blade which rotates in order to achieve a mixing action. The shape of this blade can vary according to the type of slurry being mixed. Typical shapes include propeller type (for pits and lagoons), and flat (for vertical floor stirrers). However, there are several variations on these two basic types. For instance, a flat blade may be shaped differently for pig slurry or cow slurry, to take account of the properties of the different slurry types. Similarly, propeller blades can be angled forwards or backwards to achieve push or pull stirring.
Power Source – Slurry stirrers are typically pto driven, powered by a diesel engine (e.g. tractor engine) or electric powered. Using a tractor engine is ideal in situations where it can be brought close to the mixing site (e.g. to the edge of the slurry pit or lagoon). An electric powered mixer is more appropriate when tractor access is not possible (e.g. for mixing through floor slats inside a cowshed) or where less power is needed (e.g. smaller slurry tanks).
In addition to these three primary components, a number of additional features are available:
Push-Pull Mixers – A standard mixer will either push slurry away from it, or pull slurry towards it, to achieve mixing. Some slurry stirrers have dual power inputs which allows the shaft to be rotated in both directions at different times. Switching directions periodically achieves an extra agitation effect which can be useful in stores that are difficult to mix, such as slalom systems.
Extensions – A variety of extensions are available to achieve extra height or length as needed to enable the stirrer to access the slurry, such as reaching over the edge of a slurry tower.
Slurry Mixer Options from Tramspread
Tramspread supply a variety of slurry mixers manufactured by Reck, designed to deal with a wide range of different types of slurry storage arrangement. The three main categories of mixer that we can supply are:
Slatted Floor Mixers – This type of stirrer is designed for mixing reception pits underneath pig sheds and cow sheds. Typically, the cow or pig sheds will be built with slatted floors which enable a stirrer to be inserted and retracted into different areas of the pit, without having to move livestock or lift the floor, making the job of regular slurry mixing much less disruptive to the overall operation. The mixers are electrically powered and are mounted on wheels so they can be easily moved around by one person.
PTO Mixers – PTO mixers are powered by a tractor engine and are typically used for stirring larger open pits, lagoons, tanks and towers. Where the slurry is contained in a store with steep sides, a tower mixer is available to enable the shaft to reach over the top of the tower. Where the slurry is stored in an underground pit with small access points, a folding PTO mixer is available to enable the stirrer to be more easily inserted and retracted.
Electric Stirrers – Electric mixers are designed to be used with smaller reception pits and tanks, typically below ground level. They provide a portable solution which frees up a tractor for other tasks. The mixer can be mounted on a wheeled frame and rolled to its desired access point (pictured) or affixed to the side of a store as required, via a range of different fixing mechanisms