Why McLanahan Agricultural Hydrocyclones
McLanahan Agricultural Hydrocyclones are based on patented technology used for separating, dewatering and desliming aggregates and minerals for more than 40 years. They were first introduced to the agricultural industry in 2002 to provide fine sand removal as a second step in the sand-manure separation process. By adding this secondary step in the separation process, McLanahan sand-manure separation systems have been proven to remove more than 90% of the sand from the incoming manure stream. In flush and flush-flume systems where the manure is highly diluted, a Hydrocyclone can be used as the primary means of separation with the same expected high recovery rates. This high recovery rate allows producers to recycle their sand with minimal annual sand costs. It also provides the dairy with manure effluent containing minimal bypass sand. This is important as the dairy considers long-term manure storage capacities, manure digestion or nutrient separation technologies.
McLanahan Hydrocyclones are available in multiple sizes and flow rates, beginning with a flow rate of about 680 litres per minute and ending with flow rates in excess of 7500 litres per minute. They are designed for high capacities within a small footprint, minimal wear and easy maintenance. All wetted components are lined with a natural rubber compound to reduce abrasive wear from the sand. Once the linings have become worn, components can be replaced or relined. McLanahan engineers work with customers to provide the most efficient pumping and separation system for the their needs.
How Agricultural Hydrocylcones Work
Diluted manure enters the feed inlet at a specified flow rate, which is measured as a pressure at the hydrocyclone inlet. As the manure enters the feedbox inlet, it begins to circulate at high speeds within the upper portion of the hollow cone section. As it does this, centrifugal forces act on the sand particles and pull them to the outside of the cone. A mass of sand begins to form in the hollow cylinder while gravity pulls it downward and accelerates it even more. This action further separates the sand and liquid. These heavier sand fractions then exit through the underflow regulator, sometimes called a fishtail or duckbilll, at the bottom of the cone. The remaining liquid and fine particles are pulled upward and exit the Hydrocyclone through the top of the feedbox and eventually the overflow pipe. A siphon bleed valve, attached to a hose on top of the overflow pipe, is used to regulate and adjust the amount of siphon pressure within the overflow pipe. When the valve is closed, maximum siphoning effect is felt within the Hydrocyclone and maximum dewatering occurs with the sand product. With the valve operating in the open position, the sand product will contain a much higher moisture content.
The separated sand product still contains a significant amount of moisture and organic content. Due to the high organic content, it is discharged onto an Sand-Manure Separator, which washes the organic material and produces a clean sand suitable for reuse.
Popular Applications for Agricultural Hydrocyclones
Hydrocyclones are used for grit and sand removal. They can be used as both the primary and secondary separation steps in manure separation systems, as well as to remove grit in pre-digestion and pre-nutrient separation.
Benefits of McLanahan Agricultural Hydrocyclones
- Sand removal rates more than 90%
- Reduces fine sand buildup in lagoons
- Reduces wear and tear on downstream process equipment
- Maximizes sand recovery for quicker ROI and less ongoing sand cost
- Small footprint
- No moving parts
- Simple to operate
- Replaceable, rubber-lined components for low-cost and simple maintenance
- Multiple sizes are available for wide range of flow rates
Frequently Asked Questions
What size Hydrocyclone is most appropriate for my application?
In order to get the right Hydrocyclone in place, one of our engineers will look at your application and determine the size and quantity of Hydrocyclones that are necessary to process the required flow rate. Sometimes it is better to install several smaller Hydroclones instead of one larger one, and the engineer will help to determine that. This chart shows the approximate flow rates for our most common sizes of Hydrocyclones.
Can a Hydrocyclone be used with any sand type?
Not if high removal of the sand is important. In order for us to make a fair assessment, we would need to look at a sand or grit sample prior to determining if a Hydrocyclone is appropriate or not.
The amount of sand recovered by a Hydrocyclone depends a lot on the type of sand. If the Hydrocyclone is being used to remove freestall bedding sand, we recommend using a washed concrete sand for maximimum recovery and recycling. A washed concrete sand is also good for cow health, as it doesn’t pack into the stalls and provides adequate drainage for any liquids that may come into the stalls. Our process engineering team can look at your sand type and help determine if it will separate well. This graph shows the upper and lower limit for washed concrete sand. Ideally, your bedding sand would fall within these two gradations.
What should I use to pump the manure to the Hydrocyclone?
A centrifugal pump is most often used. Due to the high pressures and abrasive nature of the sand in the manure, a pump designed to handle abrasive slurries is often preferred. McLanahan offers a complete line of Slurry Pumps that can be used and will hold up well in this application.