Study On Extrusion-spheronization Molding Equipment And Experiments For Biochar Granular Fertilizer

The traditional fertilizer has the characteristics of narrow adaptability and soil pollution, which can not meet some specific needs. That requires us to make significant efforts to develop new types of fertilizer so as to meet the needs of modern agricultural development.Biochar which can effectively make soil adsorb nutrient and improve fertility is increasingly applied to agriculture in recent years, so as to reach the aim of increasing production. The purpose of this paper is to research the shaping condition of innovative biochar granular fertilizer, shaping equipment of extrusion–spheronization and optimizing granulation process, moreover, provide reference and direction for fabrication process and manufacturing equipment of innovative biochar particle fertilizer. The following research works and conclusions were obtained:1) Feature detection of powder materiel and binder. Biochar powder and bentonite were understood through the feature detection as major powder materiel, so as to process powder materiel later. Viscosity properties of the binder were also detected. In the result, the best binder combination ratio in low concentration test was sodium lignin sulfonate: soluble starch=1:2; while in high concentration test was gum acacia: sodium alginate=1:1; it was determined that the proportion of the binder was sodium alginate: soluble starch: sodium lignin sulfonate =1:6:3 through comprehensive analysis.2) Experimental study on extrusive shaping condition of biochar granular fertilizer. The factors and levels which influence the experiment were analyzed by extrusive granulating device as the main testing equipment, besides, an orthogonal test was designed. After a comprehensive analysis of the test results, when the ratio of biochar powder and bentonite was 1:4, the compressed speed was 60mm/min and binder which concentration was 8% accounted for 40% of total material, the experimental effect was the best. It provides accurate guidance for the subsequent molding experiment of biochar granular fertilizer. After exploring the effect of extrusion aperture and spheronization on biochar fertilizer characteristics, it is concluded that increasing aperture and spheronization have a facilitating role on fertilizer characteristics.3) Design and manufacture of extrusion–spheronization machine. After determining the extrusion spheronization method, the particle principle and motion analysis of the selected scheme were analyzed. And then an extrusion spheronization granulator was designed and manufactured, which mainly including extrusion system, a cutting mechanism, spheronization system and electrical system, etc. The production capacity of 5 kg/h, screw diameter 55 mm and the ratio of length to diameter is 4. According to the replacement different aperture plates, the machine can produce 1 ~ 5mm size of the particles, while achieving material extrusion, automatic cut, rounded and automatic discharge.4) Research and experiment on granulation process of biochar granular fertilizer. Biochar granular fertilizer and molding experiments take the advantage of the extrusion spheronization granulator, exploring from the single factor and orthogonal experiments respectively in order to optimize the biochar granular fertilizer and molding process. After visual analysis and variance analysis of orthogonal test results, when the ratio of biochar powder and bentonite was 1:2.2, the extrusion speed was 8 RPM and binder which concentration was 8% accounted for 30% of total material, the experimental effect was the best.5) Feature comparison and detection on characteristics of biochar granular fertilizer. The author compared the characteristics from multiple aspects of particle between two fertilizers on the market that were made with biochar by other granulation process and the biochar granular fertilizer which was granulated according to the orthogonal test optimal scheme. Test results showed that the total biochar content and nutrient content of three particles biochar fertilizer were consistent. The biochar granular fertilizer had high tightness by means of extrusion spheronization; it has better performance in the following indicators: moisture content, compressive strength, roundness and granularity; it reached the median level on nutrient release performance; it performed poor on hygroscopicity, therefore, corresponding postprocessing should be considered to improve its hygroscopicity in later stage.