Design And Experiment Of Biochar-Based Slow-Release Fertilizer Granulating And Sieving Machine

Biochar-based slow-release fertilizer is a new type of physical-blocking,long-acting slow-release fertilizer using biochar absorption to slowly release nutrients.It has the advantages of low cost and environmental-friendly.According to requirements of the biochar-based slow-release fertilizer granulation and sieving process,a combination of forming granulation and sieving technology was proposed,and a biochar-based slow-release fertilizer granulating and sieving integral device was designed and tested,and the physiochemical properties and slow-release property of biochar-based slow-release fertilizer were studied.These studies provide theoretical basis and technical reference for the formation and efficient utilization of biochar based slow-release fertilizer.The main research contents of this topic are as follows:(1)The whole structure and key components of the biochar-based slow-release fertilizer granulating and sieving integral device were designed.The device consists of quantitative screw feeder,flat-die granulating device and plane-surface round sifter,etc.The dynamic and motion processes of screw feeding,flat-die granulating and plane-surface round rotating sieving were analyzed,respectively.And the main structure and relative parameters were settled.And a test prototype of biochar-based slow-release fertilizer granulation and sieving integrated machine device was produced.(2)A single-factor test research and analysis of the biochar-based slow-release fertilizer granulating and sieving integral device was studied.Taking productivity and density of urea biochar-based slow-release fertilizer as evaluation indexes,a single factor test about template aperture,die roll gap and bentonite binder mass fraction as test factors was developed.The results show that the smaller the die roll gap,the higher the binder mass fraction and the higher the urea biochar-based fertilizer product particle density.The urea biochar-based slow-release fertilizer products have the highest particle density When the mold roll gap is almost 0 mm,the binder mass fraction is 20%,and the template aperture is 3 mm.The productivity of the integrated device is the highest when the die roll gap is 0.5 mm,the content of binder mass fraction is 15%,and the template aperture is 5 mm.The size of the template aperture has a significant effect on the productivity and product density of the integrated device(P <0.01).The die roll gap and the binder mass fraction both have a significant effect on the productivity of the integrated device(P <0.01),and have a significant effect of the product density(P <0.05).(3)A quasi-level orthogonal test research and analysis of the biochar-based slow-release fertilizer granulating and sieving integral device was developed.Die roll gap,binder mass fraction and template aperture were selected as test factors to proceed the three-factor quasi-horizontal orthogonal tests.The results of the visual analysis method show that the important order of factors affecting productivity and product density are template aperture,die roll gap and binder mass fraction;the results of significance analysis method show that the template aperture has a significant effect on the productivity of the integral device and the density of the urea biochar-based slow-release fertilizer granule product(P <0.05),and the die roll gap has a significant effect on the density of the urea biochar-based slow-release fertilizer granule product(P <0.05);according to the comprehensive balance analysis,the device reach the highest productivity when the template aperture is 5 mm,the die roll gap is 0.5 mm,and the binder mass fraction is 15%;the product density of urea biochar base fertilizer reach the highest level when the template aperture is 3 mm,the die roll gap is 0.5 mm,and the binder mass fraction is 20%.(4)An experiment on the physiochemical and slow-release characteristics of biochar-based slow-release fertilizer granules was developed.Urea and potassium chloride biochar-based slow-release fertilizer column particles with different binder content and biochar fertilizer ratio were prepared based on biochar,and the physiochemical and slow-release characteristics of biochar-based fertilizer particles were analyzed.The results show that the binder mass fraction and the ratio of carbon fertilizer have a significant effect on the compressive strength of biochar-based slow-release fertilizer particles(P <0.05).When the biochar fertilizer ratio is 1:4,as the binder mass fraction increases,the microscopic surface pores of potassium chloride and urea biochar-based slow-release fertilizer particles decrease,and the mechanical and slow-release properties increase.When the binder mass fraction is 20%,the mechanical and slow-release properties of the two biochar-based slow-release fertilizers are the best,the average compressive strength are the maximum values of 286.78 N and 281.27 N,respectively,the nutrient leaching rate of potassium chloride biochar-based slow-release fertilizer particles and urea biochar-based slow-release fertilizer in the first 3 days were the minimum values of 45.53% and 36.87%,respectively.When the binder mass fraction is 10%,the slow-release performance of biochar-based slow-release fertilizer particles increase with the increase of biochar fertilizer ratio.When the biochar fertilizer ratio is 1:3,the nutrient leaching rates of potassium chloride biochar-based slow-release fertilizer particles and urea biochar-based slow-release fertilizer particles were the minimum values of 42.06% and 40.32% in the first 3 days,respectively.The pores on the surface of potassium chloride biochar fertilizer particles increased at first then decreased.The surface pore volume of urea biochar-based slow-release fertilizer gradually increased,and the average compressive strength was a maximum of 267.84 N when the biochar fertilizer ratio was 1:6.Considering the physiochemical properties and slow-release properties of biochar-based slow-release fertilizer particles,the mechanical properties of the fertilizer are better when the biochar-based slow-release fertilizer molding formula of bentonite binder mass fraction and biochar fertilizer ratio were 20% and 1:4 or 10% and 1:3,and the slow-release properties are the best,at the same time,it can meet the medium concentration standard specified in GB / T 23348-2009 slow-release fertilizer,and meet the market requirements.