The phosphate industry continues to gain attention as of late, as the world begins to approach peak phosphorus. With that, companies will increasingly be looking to improve upon their phosphate products and processing methods.
What follows is a basic overview of the equipment commonly used in processing phosphate rock into animal feed and fertilizer products. Some equipment features may be specific to FEECO International.
Granulation drums are the centerpiece of most phosphatic fertilizer operations. This is where material is granulated after reaction.
Granulation drums are incredibly versatile and can therefore be used to process a wide array of materials. They are used frequently throughout the agriculture industry to create a variety of inorganic fertilizer products.
How Granulation Drums Work
In fertilizer production, granulation drums work by tumbling raw material in a rotating drum. As the material cools and solidifies, the tumbling action rounds it into granules. Tumbler flights can be added to increase material agitation and create the desired product characteristics.
Flexible and corrosion-resistant drum liners can be implemented to reduce or eliminate material build-up on drum walls, and decrease the potential for damage due to a corrosive material.
In the phosphates industry, pug mills, also commonly known as paddle mixers, are used in granular fertilizer production to mix the recycle with the new raw materials, and in animal feed production to thoroughly mix, react, and granulate feed ingredients.
How Pug Mills Work
Pug mills use a folding and kneading action to thoroughly mix materials. In granular fertilizer production, they make a homogeneous blend prior to entering the granulator. In animal feed production, they facilitate the reaction between components. The thorough mixing helps to ensure a uniform product.
Rotary dryers are used prolifically throughout the phosphates industry, for drying phosphate rock, as well as for drying granular animal feeds and fertilizer products.
How Rotary Dryers Work
Rotary dryers work by cascading material in a rotating drum in the presence of a hot gas. Material lifters, or flights, lift the material, carry it over, and drop it through the hot gas stream in order to maximize heat transfer efficiency.
The use of rotary coolers is typically used in fertilizer granulation. A cooler is commonly used after the drying step to cool material exiting the dryer.
Cooling helps to bring down material temperature so it is not too hot for subsequent handling, and it also helps to prevent caking issues during storage.
How Rotary Coolers Work
Much like rotary dryers, rotary coolers cascade material in a rotating drum. Instead of heated air, however, they utilize chilled or ambient air. Here again, flights are necessary to increase heat transfer efficiency.
Hammer mills are used for both fertilizer and animal feed granulation applications. Hammer mills are used for crushing oversize granules so they can be worked back into the process as recycle.
How Hammer Mills Work
Hammer mills use a spinning shaft affixed with hammers and/or chains to break down oversize product. Hammer mills produce maximum product in the size range of minus 4 mesh down to plus 20 mesh.
High Speed Mixers
The high speed mixer is specific to the FEECO approach to animal feed granulation and is the most efficient type of reactor/mixer in the marketplace today. The addition of a high speed mixer to the pug mill provides an improved reaction and a more uniform product.
How High Speed Mixers Work
High speed mixers are comprised of a vertical chamber, through which a shaft extends. The shaft is affixed with several paddles, and operates at 300-400 RPM to provide thorough mixing and initiate the reaction before material moves on to processing in the pug mill.
Coating drums are sometimes used in the production of MAP and DAP. Coating drums coat granules with a material that improves the end product in some way, typically by reducing dusting issues, or employing an anti-caking agent.
How Coating Drums Work
Similar to rotary granulators, coating drums consist of a rotating drum through which material is fed. The material tumbles through the drum, and a spray system releases the coating agent onto the material. Tumbler flights help to increase agitation, ensuring uniform results.
Rotary kilns are similar to rotary dryers, but operate at much higher temperatures in order to cause a chemical reaction or phase change. In the phosphates industry, kilns are typically used to purify or upgrade low-grade or contaminated phosphate ore.
How Rotary Kilns Work
Rotary kilns work by heating material to the temperature at which the desired reaction will take place, and holding it there until the reaction is complete.
Pipe reactors are an acid-base reaction vessel used in the production of phosphatic fertilizers. Although they are not required in any system, in the right settings, they can provide significant energy savings, because they allow for the heat of the reaction to be captured, supplementing some of the energy required for drying.
How Pipe Reactors Work
Phosphoric acid is fed into one side of the reactor, and gaseous or liquid ammonia is fed into the reaction chamber. A hot “melt” is produced, which is sprayed onto a bed of recycle material in the rotary granulator. The captured reaction heat helps to dry the material as it tumbles through the granulator and solidifies.
As the world begins to approach peak phosphorus, the efficient processing of phosphate rock will become increasingly important. FEECO has been working in the phosphates industry since 1951, providing the best in process solutions and custom phosphate processing equipment. From material testing and process development, to custom equipment and servicing, FEECO has all of your phosphate processing needs covered.
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