In the field of compound fertilizer and functional formula fertilizer processing, the roller extrusion granulator is the core and main equipment for dry granulation. Different from the tedious process of adding water and drying required for wet granulation of discs and drums, the roller extrusion granulator relies on room temperature and high pressure forming, without the need for adding binders, no wastewater discharge, and no damage to nutrient structure. It is particularly suitable for compound fertilizer raw materials such as nitrogen, phosphorus, potassium powder, trace elements, and mineral powder. Many manufacturers have low production capacity, fragile particles, and a large amount of returned materials, mainly due to inaccurate equipment selection and non-standard production line matching. This article provides a detailed explanation of the selection techniques and a complete set of supporting solutions for a specialized roller granulator for compound fertilizer processing, helping enterprises build stable and efficient dry granulation production lines at low cost.

1、 Why is the roller extrusion granulator preferred for compound fertilizer processing?

The raw materials for compound fertilizers are mostly dry powders, with complex ratios, easy dissolution in water, and nutrient loss. Wet granulation is prone to problems such as formula imbalance, high drying energy consumption, and clumping of finished products. The roller extrusion granulator adopts a pure dry extrusion process, which does not require water drying throughout the entire process, with a short process and lower energy consumption. The formed particles have high hardness, uniform size, resistance to storage and transportation, and are not easy to pulverize. They can flexibly adapt to the production of high, medium, and low concentration compound fertilizers, support multi formula switching and processing, and meet the mass production needs of small and medium-sized fertilizer processing plants. They are also the mainstream equipment for the production of environmentally friendly compound fertilizers.

2、 Key selection points for core selection of roller extrusion granulator for compound fertilizer

Compound fertilizers contain mineral powder, acid and alkali trace elements, and have strong wear and corrosion resistance. The selection should not only focus on production capacity, but also on matching the following core parameters to ensure high molding rate and low return rate.

1. Material selection of roller skin: Alloy wear-resistant roller skin is preferred, with high hardness, corrosion resistance, and high pressure resistance. It is not easy to wear and deform during long-term processing of mineral based compound fertilizers, and the groove position does not deviate, effectively ensuring particle regularity. Ordinary carbon steel roller skin is prone to corrosion and wear, and is only suitable for lightweight materials, not suitable for mass production of compound fertilizers.

2. Squeezing pressure matching: The standard molding pressure for compound fertilizers is controlled at 20-25MPa. Insufficient pressure can cause loose and fragile particles, while excessive pressure can lead to cracking, whitening, and equipment overload. The preferred model with hydraulic pressure regulation can dynamically adjust the pressure according to different formulas and adapt to the molding of various complex powders.

3. Capacity and model matching: Small processing plants produce 1-3 tons per hour, using standard small and medium-sized models; When producing 3-8 tons in medium-sized mass production, priority should be given to widening the roller body model, ensuring uniform feeding and stable extrusion; Large production lines can adopt a multi machine parallel mode to meet the demand for high production capacity.

4. Feeding system configuration: The mixed powder material is prone to bridging and material breakage. For mass production conditions, it is recommended to use a forced spiral feeder to feed at a constant speed and compact evenly, avoiding problems such as uneven particle size and unstable molding caused by uneven feeding.

3、 Complete supporting production line plan for compound fertilizer processing

The single machine operation of the roller granulator has high losses and a large amount of material return, requiring the use of closed-loop supporting equipment to form an automated production line and achieve 100% material utilization.

1. Preprocessing equipment: The automatic batching system accurately proportions nitrogen, phosphorus, potassium, and trace elements to eliminate manual errors; The agglomerated raw materials are refined by a grinder to ensure that the powder is fine and uniform; The mixer thoroughly mixes materials to solve the problems of layering of light and heavy powders and uneven formula.

2. Core molding equipment: The roller extrusion granulator completes high-pressure dry molding, producing standard particles in one step without the need for drying and cooling, greatly simplifying the production process.

3. Screening and return system: The drum screening machine screens qualified particles, and the crushed and powdered materials are re pelletized through the conveyor reflux mixer, resulting in closed-loop production without raw material waste and significantly improving the finished product qualification rate.

4. Finished product packaging equipment: Automatic quantitative packaging machine with automatic weighing, sewing, counting, suitable for batch shipment of granular compound fertilizers, saving labor costs and improving shipping efficiency.

4、 Standardized production process flow

Raw material impurity removal → automatic precise batching → material mixing and blending → high-pressure extrusion granulation by rollers → particle screening and grading → powder material recycling → automatic packaging of qualified particles. The entire process does not require a drying step, has low energy consumption, no pollution, and can operate continuously for 24 hours, making it suitable for large-scale production of compound fertilizers.

5、 Selection and Production Common Pit Avoidance Guide

Many manufacturers blindly use universal roller skins and adjust pressure arbitrarily, resulting in poor particle quality and high equipment failure rates; Neglecting the ingredient mixing process, uneven mixing of materials leads to nutrient imbalance in the finished product; No return material system, serious powder waste, and low production capacity. In production, it is necessary to strictly match the special configuration of compound fertilizers, standardize pressure parameters, and equip a closed-loop screening and return system to ensure stable and efficient operation of the production line.

VI. Summary

The roller extrusion granulator is an equipment for dry processing of compound fertilizers, and the selection core lies in adapting to wear-resistant roller skins, standard extrusion pressure, matching production capacity and feeding system. A complete set of supporting equipment for batching, mixing, screening, and material return can be used to build a standardized production line with low energy consumption, high molding rate, and zero waste, effectively reducing production costs, improving product quality and market competitiveness, and adapting to the large-scale production of various compound fertilizers and functional formula fertilizers.