NPK fertilizers - Types, Manufacturing methods
- 1. PL.Sriram , G.Sudarshan Recent Developments in Fertilizer industry
- 3. • Nitrogen fertilizers • Crushed animal bones (P-rich) • Leibig – Crushed bones with dilute sulphuric acid - Ph0sphate fertilizers • Invention of Ammonia by Haber and Bosch History of Fertilizers
- 4. • Phosphate rock (RP) is the main source of phosphorus in fertilizers. • First deposits of phosphate rock were discovered in the early 19th century and its mining started in 1867 in South Carolina, USA. • Rock phosphate was first used for direct application for more than 150 years • Research on rock phosphate for direct application as a fertilizer started over 100 years ago Phosphate Rock : The natural Non – Renewable Source of Phosphate
- 6. •The main nitrogen-based straight fertilizer is ammonia or its solutions •Ammonium nitrate (NH4NO3) is also widely used •Urea is another popular source of nitrogen, having the advantage of being a solid and non-explosive Single Nutrient Fertilizers
- 7. These fertilizers are the most common ones. They consist of two or more nutrient components Major two-component fertilizers provide both nitrogen and phosphorus to the plants. These are called NP fertilizers. The main NP fertilizers are monoammonium phosphate (MAP) and diammonium phosphate (DAP). The active ingredient in MAP is NH4H2PO4. The active ingredient in DAP is (NH4)2HPO4. About 85% of MAP and DAP fertilizers are soluble in water. Multi Nutrient Fertilizers
- 8. NPK fertilizer is usually thought of as a chemical fertilizer, but NPK applies to any soil amendment that supplies Nitrogen, Phosphorous, and Potassium, including organic fertilizers Plants need nitrogen for leaf growth, phosphorus for root formation, stem growth, and fruiting, and potassium for flowering and plant immunity Organic NPK fertilizers can be slow-releasing or fast- releasing. NPK Fertilizers
- 9. • Granulation with a pipe reactor system Mixed Acid Route Nitrophosphate Route Methods of NPK Fertilizer Manufacture
- 10. Granulation with a pipe reactor system
- 11. Granulation
- 12. • Classical Granulation loop • Two pipe reactors • Phosphoric + Sulphuric acid – Neutralized by ammonia
- 13. Solid raw materials - potassium chloride, potassium sulphate, superphosphate, secondary nutrients, micronutrients Granulation and Drying section
- 14. Granulation and Drying section • Concentrated ammonium nitrate solution may be added directly into the granulator – Ammoniation • A pipe reactor fitted in the dryer is fed with phosphoric acid and ammonia • N/P mol ratio is 1.00 - MAP
- 15. • MAP produced consists of very fine particles, passes via the cyclones , screens back to the granulation drum • The granules obtained are dried in a drying section using a heated air stream Granulation and Drying section
- 16. Screening, Crushing, Cooling, Coating • Oversize • Undersize • On-spec fraction
- 17. • Gases from the granulator and dryer are scrubbed in venturi scrubbers with recirculating ammonium phosphate or ammonium sulpho- phosphate solution • The scrubber liquor which is being recycled is fed to the pipe reactor in the granulator. Gas scrubbing, Dust removal
- 18. • The gases coming from the dryer are de-dusted in high efficiency cyclones to remove the majority of the dust before scrubbing. • The air coming from the cooling equipment is generally recycled as secondary air to the dryer after de- dusting Gas scrubbing, Dust removal
- 19. Mixed Acid Route
- 20. •Cheap raw materials such as phosphate rock •Digestion of phosphate rock with nitric acid resulting in a solution of phosphoric acid and calcium nitrate •Gases such as oxides of nitrogen and fluorine compounds are formed during the digestion, depending on the type of phosphate rock. Digestion reactors
- 21. • Raw materials such as phosphoric, sulphuric and nitric acids are added after the digestion (Exothermic) •The slurry is ammoniated with gaseous ammonia and after neutralization, other components such as ammonium phosphates, superphosphates, ammonium sulphate, compounds containing potassium and magnesium are added Digestion reactors
- 22. Ammoniation reactors • The design of the reactor battery can vary from a few large reactors to many, smaller reactors • Common for all the designs of the reactor battery is that the row of reactors ends with a buffer tank.
- 23. Mixed acid route
- 25. Solid raw materials • The main solid raw materials are potash and phosphate rock • These raw materials are transported to the production site by ships, trains or lorries. • Grab cranes are traditionally used for the unloading of ships and with this method there is the risk that some fine material may spread to the environment in the harbor area. •It is recommended that closed unloading methods Ship unloading
- 26. Unloading of rail waggons or lorries Waggons/ Lorries Hoppers Conveyors
- 27. • Raw materials are stored in closed buildings or silos • Materials in storage are handled by payloader, scraper or crane •Bulk storage is in closed buildings with walls to separate different grades of product • Fertilizers are hygroscopic and thus it is recommended that the storage atmosphere be air-conditioned Storage
- 29. • The nitrophosphate process was a method for the industrial production of nitrogen fertilizers invented by Erling Johnson in the municipality of Odda, Norway around 1927. • Although Johnson created the process while working for the Odda Smelteverk, his company never employed it. Instead, it licensed the process to Norsk Hydro, BASF, Hoechst, and DSM. • Each of these companies used the process, introduced variations, and licensed it to other companies. Due to the alterations of the process by the various companies who employed it, the process is now generally referred to as the nitrophosphate process. The Odda process - Introduction
- 30. Phosphate sources must be converted into a form which can be taken up by plants This can be achieved by using the integrated “Nitrophosphate” process which produces compound fertilizers containing ammonium nitrate, phosphate and potassium This process aims to produce nitrate-containing straight and compound fertilizers starting from rock phosphate and using all the nutrient components in an integrated process without solid wastes and with minimal gaseous and liquid emissions. Goals of the process
- 32. The Main Steps of NP process is as under • Rock Phosphate Storage and Handling • Dissolution of rock phosphate with nitric acid • Crystallization of Dissolving solution and separation of calcium nitrate crystals from nitrophosphate acid • Ammoniation (i.e. neutralization of nitrophosphate acid) • Prilling of the slurry and conditioning of the product Summary of processes involved
- 33. Rock phosphate is weighed and added into the first dissolving reactorwhere it is mixed with the proper amount of Nitric acid plus wash acid. In order to avoid foaming during the reactions, required quantities of antifoaming agent is sent to the first dissolving reactor The phosphate solution is cooled to about 400C by means of cooling water and fed to the crystallization lines A, B, C, D, E and F. In the crystallizers calcium nitrate is crystallized out as calcium nitrate tetra hydrate crystals The mother liquor from filter drum is pumped to the neutralizers. To obtain the proper NP ratio in the end product, a certain amount of ammonium nitrate solution from the calcium nitrate conversion plant is recycled to this tank Process description
- 34. The neutralizer is also fed with a proper amount of ammonia in order to effect adequate neutralization. The amount of ammonia is controlled by an automatic pH control Gases leaving the neutralizer are washed in scrubber. After neutralization, the NP solution is concentrated in evaporators The Melt from the evaporator is fed to a prilling tower The prills are removed from the bottom of the tower by means of a scraper at about 950C Prills are conveyed by means of a belt conveyor to a cooling unit, cooling is done by air induced by a blower Cooled Product is sent to Handling plant for Bagging and storage. Process description
- 36. This process on the core is still being by almost all industries till date The basic underlying acidulation of Phosphate rock is a fixed constant But process conditions are optimized At the same time recovery of byproducts is made more efficient Let us look at some of the developments…. Developments in process
- 37. Morocco phosphate rock is preferred over Egyptian Rock Phosphate and Algerian Rock Phosphate due to following reasons- High P2O5 due to which low rock consumption / ton of NP production Low silica contents increases plant on- stream hours and less erosion Ideal particle size distribution No adverse affect observed while testing this rock phosphate Choice of Phosphate rock
- 39. CN centrifuges were used for separation of CN crystals from mother liquor solution Very high failure rate due to which they have high maintenance and operational cost The common maintenance problems were damaging of the separation screens, damaging of solution pusher ring and oil leakages due to vibrations These screens were replaced with slow moving rotary filter drums. Double filtration technique was adopted successfully in the year 1996 with Komline Sanderson filter drum of USA. CN Centrifuge design improvements
- 40. Urea solution is added in first dissolving reactor to control NOx in off –gases Urea solution addition started in the year 2005 in dissolving reactors Now, Nox emission in stack < 10 ppm before urea addition it was 200 ~ 300 ppm. Urea Control system
- 43. Questions ?