​Optimization of Copper-Based Nutrient Protectant Suspension Agent Production

Abstract

This study optimized the process for preparing copper-based nutrient protectant suspension agents using a sand mill through experimental design and analysis. Four key factors were investigated: slurry mass fraction, grinding speed, grinding media-to-slurry mass ratio, and grinding time. The goal was to enhance the suspension and stability of these agents, which are vital for crop protection. The results revealed optimal conditions and provided insights for the production of copper-based nutrient protectants.

Introduction

Copper-based nutrient protectants play a crucial role in safeguarding crops against various diseases. They primarily consist of copper hydroxide, a potent agent used in a range of agricultural applications. The development of efficient suspension agents is essential to ensure the effective dispersion and adhesion of copper-based compounds on plant surfaces. This study aimed to optimize the production process of copper-based nutrient protectant suspension agents using a sand mill, a key step in their manufacturing.

Materials and Methods

1. Materials:

• Copper-based nutrient protectant composition: Copper hydroxide (60%), urea (32%), EFW wetting agent (2%), D-425 dispersant (3%), and other fillers (3%).

• EFW and D-425 were sourced from AkzoNobel Shanghai Co., Ltd.

2. Instruments and Equipment:

• SFJ400 experimental dispersing sand mill (2 L chamber, 400 mm disc diameter).

• Zirconium oxide beads (2.5-3.0 mm) as grinding media.

• BT-9300H laser particle size analyzer (Dandong Baite Instrument Co., Ltd.).

3. Experimental Methods:

• Orthogonal experimental design (L9(34)) with four factors at three levels.

• Single-factor experiments to identify optimal grinding conditions.

• Evaluation of product performance indicators, including D50 and D97 values, specific surface area, and suspension rate based on relevant standards.

Results and Discussion:

1. Effects of Factors in Orthogonal Experiments:

• Grinding speed exerted the most substantial influence on particle size.

• The grinding media-to-slurry mass ratio significantly affected the specific surface area.

• Slurry mass fraction had a minor impact on both particle size and specific surface area.

2. Effects of Individual Factors on Particle Size and Specific Surface Area:

   2.1. Effects of Slurry Mass Fraction:

   2.2. Effects of Grinding Speed:

   2.3. Effects of Grinding Media-to-Slurry Mass Ratio:

   2.4. Effects of Grinding Time:

• Longer grinding times decreased particle size, increased specific surface area, and improved grinding efficiency.

• After 80 minutes of grinding, both particle size and specific surface area remained stable.

• A ratio of 1.5:1 reduced particle size and increased specific surface area.

• Further increases in the ratio had minimal effects on particle size and specific surface area.

• Higher grinding speeds (up to 1,500 rpm) led to notable changes in particle size and specific surface area.

• Beyond 1,500 rpm, particle size and specific surface area stabilized.

• Increasing slurry mass fraction minimally impacted particle size.

• Specific surface area consistently exceeded 4,000 m2/kg across all tested mass fractions.

3. Optimal Grinding Conditions and Product Performance Indicators:

• Optimal conditions: Slurry mass fraction of 60%, grinding speed at 1,500 rpm, grinding media-to-slurry mass ratio of 1.5:1, and grinding time of 80 minutes.

• Under these conditions, the suspension rate consistently exceeded 90%, meeting relevant standards for copper hydroxide suspension agents in terms of suspension rate, dispersibility, water adaptability, and water temperature resistance.

Conclusion

This study successfully optimized the production process for copper-based nutrient protectant suspension agents using a sand mill. By investigating key factors, we identified optimal conditions for producing highly effective agents. The findings provide valuable insights into the resource-efficient and environmentally friendly production of copper-based nutrient protectants, offering numerous benefits for crop protection and agriculture.