不同肥料粒形特征对肥料球度的影响

为明确肥料粒形特征之间的相互关系,该文通过单因素及中心组合试验研究肥料不同粒形特征对肥料球度的影响。首先,通过农业物料粒形分析仪测定肥料长、宽、厚、等轴率、薄片率、磨圆度及球度;其次,通过单因素方差试验确定不同粒形特征与肥料球度之间的相关性;最后,以肥料等轴率、薄片率和磨圆度为主要影响因素,采用Box-Behnken中心组合试验,建立关于肥料球度的数学模型,通过回归统计方差、响应面和等高线分析各影响因素与肥料球度之间的相互关系。结果表明:肥料球度与等轴率、薄片率及磨圆度之间能建立显著性较高的多元回归方程(R2为0.94);各因素对肥料球度影响程度从高到低依次为等轴率、薄片率、磨圆度,且当等轴率在0.98~1.00,薄片率在0.92~0.95,磨圆度在0.85~0.88范围内时,肥料球度最高,达到92.9%。研究结果可为肥料生产和质量检验提供理论依据。

Effect of different fertilizer shape characteristics on fertilizer sphericity

A fertilizer that served as an important agricultural input, become rank first in the world in terms of Chinese production and utilization, further ensuring national food security and agricultural productivity. However, there are various effects of the shape characteristics of fertilizers on the appearance quality, strength, fluidity and the efficiency of mechanical fertilization in modern mechanized agriculture. If the sphericity of particles in a fertilizer is high, the strength of the fertilizer will be high, indicating hardly being deformed and/or broken. If the roundness of particles in a fertilizer is high, the porosity of the fertilizer will be large, indicating the better heat dissipation and flow effect. There are significant influences of particle shape and pore structure on the diffusion of salt ions in the fertilizer, while in turn the agglomeration of the fertilizer can affect the pore structure that caused by the accumulation of the fertilizer. Therefore, the effects of different shape characteristics on the fertilizer sphericity were studied by using single-factor and central combination tests, in order to clarify the relationship between various shape features and mechanical properties in the fertilizer. Firstly, the length, width, thickness, equiaxed rate, flake rate, roundness and sphericity of fertilizers were measured by the shape analyzer for agricultural materials. Secondly, the correlation coefficient between different shape characteristics and the fertilizer sphericity was determined by the single-factor variance test. Finally, taking the equiaxed rate, flake rate, roundness of fertilizers as the main influencing factors, the mathematical model of the fertilizer sphericity was established by Box-Behnken central combination test, and then the relationship between these factors and fertilizer sphericity was analyzed by the approaches of the regression statistical variance, response surface and isoline. The simulated results showed that a significant multiple regression equation could be fitted between the fertilizer sphericity and the equiaxed rate, flake rate, and roundness. The influence degree of each factor on the fertilizer sphericity from high to low was in the order of the equiaxed rate, flake rate, and roundness. When the equiaxed rate was in the range of 0.98-1.00, the flake rate was in the range of 0.92-0.95, and the roundness was in the range of 0.85-0.88, while the fertilizer sphericity was the highest, reaching over 92.9%. In the same batch of the compound fertilizer, 50 particles were randomly selected as verification samples, and the measured sphericity of fertilizer was obtained through various experiments. The predicted sphericity of fertilizer was achieved by the sphericity regression equations, while the accuracy of the sphericity model was evaluated by the error rate. The test results show that the maximum positive and negative error rate between the measured- and predicted sphericity of fertilizer was within 9%, indicating that the test results were consistent with the simulated values from the response surface analysis, as well verifying the proposed mathematical model. Therefore, a novel method for the indirect measurement of the fertilizer sphericity was proposed, which can provide significantly theoretical fundamentals for the production and quality inspection of fertilizers.