Mixed Fertilizer Zone – Test Your Knowledge 11.10

How to improve the balling rate of high-concentration compound fertilizers? What are the main factors affecting the production of high-concentration compound fertilizers? We have identified the following key aspects: 1) Production equipment； 2) Processes, technologies ； 3) Physicochemical properties of raw materials ； 4) Production formula and added conditioners ； 5) Inlet and outlet air temperatures of the dryer, air volume ； 6) Temperature of the granulated material, amount of liquid phase ； 7) Material flow rate ； 8) Return material ratio ； 9) Qualities of operators ； 10) Climate conditions. Only by integrating all these factors into the production of well-made fertilizer pellets can high-yield and high-quality compound fertilizers be produced, with none of them being dispensable. 1 Improving the performance of equipment used in compound fertilizer production is the foundation for increasing the balling rate. 1) First and foremost, it is necessary to ensure the quality of such equipment. When purchasing equipment, choose manufacturers that have well-equipped facilities, comprehensive testing methods, and reliable product quality, and make the purchase under the guidance of technical personnel with practical experience. 2) Ensure high quality in equipment installation. 3) Choose a model with excellent performance. There are many types of equipment for producing compound fertilizers, and each type has its own strengths. Purchasing a complete set of equipment from just one manufacturer clearly has its limitations; only by combining the advantages of various devices on a single production line can the best results be achieved. Good craftsmanship must be reflected through good equipment. 4) The layout of the equipment should be reasonable. The equipment layout must be designed by a professional design team with experience in compound fertilizer production. 5) Personnel responsible for equipment management and maintenance must possess professional skills, and a dedicated person should be assigned to take good care of the equipment to ensure its high rate of integrity. 2 Choosing phosphoric ammonium salt with good viscosity as a raw material is a prerequisite for improving the balling rate. The balling of high-concentration compound fertilizers relies mainly on the viscosity of phosphoric ammonium salt and the conditioning agents, and the quality of this viscosity directly affects the balling rate of the compound fertilizers. Therefore, when purchasing ammonium phosphate, it is necessary to consider not only the nutrient content and price but also its viscosity. Based on practical production experience, diammonium phosphate has better viscosity than monammonium phosphate, and among domestically produced diammonium phosphates, the products from Anhui Tongling Phosphatic Ammonium Factory have the best viscosity. 3 Ensuring the fineness of raw materials and recycled materials is fundamental to improving the balling rate. The higher the mesh size of the raw materials, the better the viscosity of the material, which makes it particularly important to enhance the efficiency of the crusher. At present, most manufacturers in our country use chain crushers. Their advantages include high production capacity and excellent crushing performance, making them relatively ideal equipment for crushing fertilizers. It is important to regularly check the wear of the chains during use, and to repair any damage as soon as it is detected. It is necessary to check daily whether the material inside the crusher is sticking to the walls; if such sticking is detected, it must be cleaned manually promptly. Our institute currently has anti-adhesion wall crushers, which can **reduce the workload**. The horizontal double-axis chain crusher is particularly effective at crushing large pieces of ammonium chloride, as well as the coarse particles and other lump-shaped fertilizers present in the recycled material; it has little effect on granular ammonium phosphate, urea, and potassium chloride. If phosphatic ammonia, urea, and potassium chloride need to be crushed, a cage crusher or a JF-type table salt grinder can be used; these devices are suitable for crushing materials with high strength, high viscosity, and strong hygroscopicity. As is well known, hot return material is easier to crush than cold return material; therefore, in our design, a hot-material sieve is used for the coarse screening, allowing the coarse material to enter the crusher quickly while still being hot, thereby improving the crushing efficiency. In the design, fine return material does not pass through a crusher. The fine sieve uses a clear pore size of 2.5 mm × 2.5 mm; during screening, all material smaller than 2 mm must be screened out and returned as feed, in order to provide enough core material for the next round of granulation. As the core material for granulation, the particle size should be between 1 and 2 mm ； As packaging material outside the core, it is better to use a higher mesh count. 4. Even mixing of materials is an important measure to improve the balling rate. Even mixing of materials means that the fresh materials used, namely nitrogen, phosphorus, and potassium, should be well mixed together; it is advisable to use two mixers in the design in order to extend the mixing time ； Secondly, it is necessary to ensure a stable flow rate of fresh material, so that the recycled material and the fresh material can be combined in a thorough and balanced manner throughout the process; the mixing should not be intermittent. The fine particles in the recycled material are mostly potassium and nitrogen, which have poor cohesion and are therefore the most difficult materials to form into balls. In contrast, fresh material has better cohesion, making it easier to form larger balls during production. Thorough mixing of fresh material with recycled material is an effective measure to prevent the formation of large balls as well as an excess of fine particles. Recycled material should be returned using conveyor belts, and efforts should be made to avoid using vehicles for this purpose. 5 A stable material flow rate is an important means of improving the balling efficiency. Installing a storage hopper and a flow controller in front of the granulator enables stable control of the material flow rate. Only when the material flow rate into the granulator is stable can the moisture content during granulation be kept under control. Some factories add a feeder in front of the granulator, using the rotation of the feeder to control the flow rate, thereby maintaining a relatively stable flow rate over time. The flow rate should also be determined based on the drying capacity, and must not exceed it, in order to ensure that the moisture content w(H2O) of the final high-concentration compound fertilizer remains ≤2. 6 Appropriate material moisture and granulation temperature are key to improving the balling rate; the granulation stage is a critical factor in determining production volume. Only by adjusting the temperature and moisture content of the granulation material to the optimal levels can normal granulation in the granulation zone be ensured. Therefore, it is necessary to pay attention to the temperature and moisture content of the material at the discharge point of the granulator; the optimal temperature for the material in the granulation area is 60–65°C. For the normal granulation of high-concentration compound fertilizers, the moisture content of the material should be between 3.59/6 and 5.59/6; the appropriate moisture level is determined based on the type of raw materials. Once this level is established, any adjustments to the moisture content should be made in small increments, with variations of less than 0.5. It is better to aim for a drier condition rather than a wetter one, in order to quickly reach the optimal moisture level. Excessive liquid content can cause the material to form large balls, as well as lead to sticking of the material to the walls of the dryer, which in turn makes it difficult for the conveyors and screens downstream to function properly. If the material remains too dry for an extended period, fine powder can easily be drawn into the dust removal chamber. Most of the fine powder consists of sticky materials, while the remaining materials generally have lower stickiness. An increase in the amount of recycled material disrupts the ratio between fresh material and recycled material, which can lead to a vicious cycle. At the same time, it is necessary to pay attention to the condition of the material at the outlet of the dryer as well as the balling rate; visually, the optimal level for the balling rate is such that particles larger than 4.75 mm account for 15.9/6, those between 1 and 4.75 mm account for 70%, and fine particles smaller than 1 mm account for 15.9/6. 7 An appropriate air volume and stable furnace temperature are prerequisites for improving the balling rate. The amount of air directly affects the drying efficiency. The dryer has a high air flow rate, resulting in excellent drying performance. The air volume is generally calculated based on the cross-sectional area of the dryer barrel, at 7,000 m per square meter of the dryer’s cross-section. /h is appropriate; the wind speed should be less than 2 m/s, as too high an air flow can easily draw the powder out of the cylinder. When selecting a fan, it should be purchased based on the aforementioned air volume. In terms of air volume, the supply at the front and extraction at the back should remain roughly balanced, so as to maintain a slight negative pressure inside the dryer and prevent smoke from escaping. Currently, many factories suffer from issues such as insufficient air supply at the front and excessive suction force at the back; phenomenologically, this is reflected in a large temperature difference at the rear end of the dryer. The air intake ducts should be compatible with it; the air volume should not be affected by the narrowness of the ducts. Control valves should be installed on the ducts before or after the fan to facilitate adjustment of the air volume. For example: the furnace gas blower should be equipped with a valve at its inlet; this valve allows an increase in the airflow from the blower located at the bottom of the furnace when the furnace temperature is too low, thereby raising the temperature inside the furnace ； If the temperature is too high, the air volume of the blower can be reduced to lower the temperature inside the furnace, thereby keeping the temperature of the dryer’s exhaust gases within the specified range; valves installed can be used for control and adjustment. In formulations without urea, the furnace temperature is determined based on the moisture content of the finished product after drying. The appropriate moisture content of the dried finished product is around 1.5 to 2; if the W(H2O) value of the finished product exceeds 2.9/6, then the furnace temperature should be increased, with regard to the W(H2O) value

When the speed of the granulator and the inner retaining ring are suitable, check the formula – the proportion of viscous materials in it, the proportion of sandy materials, and the liquid phase value； Conditions of the returned material, such as the ratio of coarse to fine returned material

Fei’s article was written by him himself; it’s good, so extra points

This post was last edited by huchsh on 2009-11-10 09:51. 1. Reduce load； 2. Amount of material to be retrieved ； 3. Improve granulation conditions: humidify, increase temperature, and raise the speed of the granulator ； 4. Add some finished granules (unwrapped) if necessary.

I believe that the material should initially exist in the form of small particles within the granulator; this way, as it rolls around in the granulator, friction is generated, leading to the formation of balls.

This post was last edited by hanermin on 2009-11-10 at 12:13. The low granulation rate is related to the raw material formula, as well as the amount of steam added.

1) Increase the amount of steam supplied appropriately, maintain the steam pressure at 0.6 MPa, and raise the operating temperature slightly； 2) Slightly increase the return material ratio to bring it close to 4 ； 3) The steam pressure in the insulation jacket of the pipeline carrying the urea melt to the granulator should be no less than 0.3 MPa, to ensure that the temperature of the urea melt at the nozzle remains above 110°C. The pressure of the urea melt at the nozzle should also be controlled in order to adjust the spraying distance, thereby preventing excessive atomization and early cooling ； 4) Add a conditioning agent to the ingredients to improve granulation conditions. 1# hanermin

Adjust the amount of steam and washing liquid, and strictly control the granulation temperature and humidity. If the results are not satisfactory, check the ratio of the ingredients in the formula

Let’s talk about the drum: checking whether the combination of raw materials is appropriate, whether the liquid phase used for granulation is suitable, the internal structure of the granulator, and the speed of the granulator, among other things

Let’s learn*learn*, and see what insights everyone has