利用硅灰石制备硅肥的研究

发布时间：2018-02-04 11:59

  本文关键词： 硅灰石 硅肥 助熔剂 动力学 机理研究 盆栽试验　出处：《华南理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：硅是农作物生长不可缺少的第四大营养元素,是组成岩石矿物的一种基本元素,广泛存在于自然界中,但是此种硅元素几乎都以结晶态和无定形态存在,不能被植物直接吸收。我国土壤中缺少硅元素的耕地面积约占总面积的50%以上,而目前我国硅肥的年生产能力不高,远不能解决我国耕地严重缺少硅的问题。因此,利用难溶性含硅矿物生产硅肥,满足国内市场对硅肥的需求是当务之急。本研究以硅灰石和白云石为主要原料,配伍以为助熔剂制备硅肥,并对工艺条件如物料配比、焙烧温度和时间等因素进行了初步探讨。实验利用优化后的硅钼蓝分光光度法测定硅肥中有效二氧化硅的含量,并采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、红外吸收光谱(FTIR)、电子探针(EPMA)、同步热分析(TG-DSC)等方法详细分析了原材料和焙烧产物的物化性质。此外,本文对硅灰石与白云石的反应机理进行了探讨并利用动力学的方法研究了助熔剂对硅灰石-白云石反应体系的影响。结果表明:(1)优化后的硅钼蓝分光光度法操作更为简便快捷、准确。溶解样品时称样量宜低于0.2 g,振荡频率宜采用170-190 r/min,用2%的柠檬酸溶液作为浸取剂提取硅肥中的有效硅成分更具有现实意义。优化后的硅钼蓝分光光度法精密度和准确度良好,多次重复测定的极差小于0.6%,标准偏差小于0.2%,加标回收率为98.5%-101.3%。(2)最佳物料配比为n(硅灰石):n(白云石):n(助熔剂)=1:0.3:0.4;最适宜的焙烧条件为1000°C、1 h,在此条件下,有效二氧化硅的含量为21.6%。焙烧后的硅灰石由针状和短柱状转变为短柱状,呈相互交生状,内表面积增大,硅灰石表面被活化。焙烧产物的主要物相为CaSiO3(CS)、Ca2SiO4(C2S)、Mg2SiO4、Ca3Mg(SiO4)2(C3MS2)和Ca2MgSi2O7(C2MS2),它们在5 g/L的柠檬酸溶液中,其有效二氧化硅、钙和镁等成分几乎全部溶出,即以它们为主要成分的硅肥即使在低浓度的有机酸(与土壤环境相似)条件下也能释放肥效,技术上可行,具有实际指导意义。(3)助熔剂对硅灰石-白云石反应体系有重要的作用,提高了体系的反应速率。助熔剂的添加使得白云石的分解温度和硅灰石与白云石发生反应的初始温度分别降低了22°C和21°C。从动力学角度,硅灰石-白云石体系在助熔剂作用下热分解的过程符合金斯特林格方程,助熔剂将硅灰石-白云石体系的表现活化能从106.89 kJ/mol降低到90.64 kJ/mol。(4)硅肥对小白菜的株高、根系生长以及生物量影响较大,施入硅肥量1‰的盆栽比空白组在株高、根重和生物量上分别增加了48.8%、49.6%、102.4%。施入适量的硅肥能够提高小白菜的发芽率,但是过量会导致烧苗现象,降低发芽率。从实际土壤情况和经济效益方面考虑,可将100 kg/亩的施入量作为农田施肥指标。
[Abstract]:Silicon is an indispensable nutrient element in the growth of crops and a basic element of rock minerals, which widely exists in nature, but it almost exists in crystalline and amorphous forms. It can not be directly absorbed by plants. The area of cultivated land lacking silicon element in our country accounts for more than 50% of the total area, but the annual production capacity of silicon fertilizer in our country is not high at present. Therefore, it is urgent to use insoluble silicon-containing minerals to produce silicon fertilizer and to meet the domestic market demand for silicon fertilizer. Wollastonite and dolomite are the main raw materials in this study. The mixture is used as flux to prepare silicon fertilizer, and the technological conditions such as the ratio of materials are given. The factors such as calcination temperature and time were preliminarily discussed. The content of effective silica in silicon fertilizer was determined by optimized silicomolybdate blue spectrophotometry, and X-ray powder diffraction (XRD) was used. Scanning electron microscope (SEM), infrared absorption spectroscopy (FTIR), electron probe (EPMA). The physical and chemical properties of raw materials and roasted products were analyzed in detail by simultaneous thermal analysis (TG-DSC) and other methods. The reaction mechanism of wollastonite and dolomite was discussed and the effect of flux on wollastonite dolomite reaction system was studied by kinetic method. The optimized silicon molybdenum blue spectrophotometry is more convenient and rapid. The sample size should be less than 0.2 g and the oscillation frequency should be 170-190 r / min. The extraction of effective silicon from silicon fertilizer with 2% citric acid solution is of practical significance. The precision and accuracy of the optimized silicon molybdenum blue spectrophotometry are good. The range difference of repeated determination is less than 0.6 and the standard deviation is less than 0.2%. The optimum material ratio is n (wollastonite: n) (dolomite: n) (flux 1: 0. 3: 0.4; flux: 1: 0. 3: 0. 4) the standard recovery rate is 98.5- 101.3%, and the optimum material ratio is n (wollastonite: n). The optimum calcination condition is 1000 掳C ~ (-1) h, under which the effective silica content is 21.6. the calcined wollastonite changes from needle-shaped and short column-shaped to short column-shaped, and it is intersected. The surface of wollastonite is activated with the increase of internal surface area. The main phase of calcined product is CaSiO3C2SiO4C2SiO4 and Mg2SiO4. Ca3MgSiO2C3MS2) and Ca2MgSi2O7C2MS2N, which are effective silica in 5 g / L citric acid solution. Almost all the components such as calcium and magnesium are dissolved, that is, silicon fertilizer with them as the main component can release fertilizer efficiency even under the condition of low concentration of organic acid (similar to soil environment), which is technically feasible. The flux has important effect on wollastone-dolomite reaction system. With the addition of flux, the decomposition temperature of dolomite and the initial temperature of reaction between wollastonite and dolomite were reduced by 22 掳C and 21 掳C. The process of thermal decomposition of wollastone-dolomite system under flux action accords with the Kingstringer equation. Flux reduced the apparent activation energy of wollastone-dolomite system from 106.89 kJ/mol to 90.64 kJ / mol 路m.4) the plant height of pakchoi treated with silicon fertilizer. The plant height, root weight and biomass were increased by 48.8% and 49.6% in potted plants with 1 鈥，

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