镁还原渣制备硅钙镁复合肥可行性及提高有效硅含量的研究
发布时间：2019-03-25 18:28
【摘要】：镁还原渣是硅热还原法炼镁产生的工业废渣，主要组成为SiO2、CaO及MgO。硅热还原法炼镁属于高耗能、高污染行业，生产1t原镁需消耗11t白云石、10t左右煤炭、1.2t硅铁，同时排放35t CO2气体和0.2t SO2气体，产生7t左右镁还原渣。2014年，我国原镁产量87.38万吨，产生600余万吨镁还原渣。 镁还原渣易粉化，水化溶液显碱性，严重污染环境。随着镁还原渣的大量排放堆积，不仅造成大量资源流失，而且占用了大量土地资源、破坏了地貌和植被。镁还原渣随着雨水的冲淋汇入江河湖泊对农作物和周围环境造成了极大的影响，严重危及到人类的身体健康及农作物的生长。同时，镁还原渣含有丰富的土壤缺乏的营养元素，但不能直接被农作物吸收。 本文针对上述问题，首先对镁还原渣制备硅钙镁复合肥的可行性进行了研究，然后对提高镁还原渣中有效硅的含量进行了研究，并采用XRD、SEM、紫外光谱等对实验结果及机理进行了分析，结果表明： （1）在查阅大量文献的基础上，结合镁还原渣的理化特性，初步制定了镁还原渣制备硅钙镁复合肥的工艺流程。 （2）镁还原渣中含有农作物所需的硅钙镁元素，其组分能够满足硅钙镁复合肥所需的基本元素及含量，，且重金属元素含量极少，满足制备硅钙镁复合肥的基本要求。 （3）镁还原渣加入石英砂焙烧后发生相变，由反应活性较低的Ca2SiO4转化为反应活性较高的CaSiO3，有利于用盐酸溶解。焙烧时，添加13.53%石英砂，即镁还原渣中SiO2的含量达43%时，焙烧所需的温度最低，为1460℃。 （4）镁还原渣酸浸采用的盐酸浓度为4mol/L时，盐酸可使镁还原渣中的氧化镁、氧化钙、氧化铁全部溶解进入溶液。 （5）酸浸渣在温度为140℃~400℃的焙烧过程中发生硅酸体系分解为二氧化硅的化学反应过程以及部分无定形二氧化硅的晶格结构被破坏，发生晶格重构的过程。低于140℃时，酸浸渣仅脱去物理吸附水；高于400℃时，酸浸渣中无定形二氧化硅晶型转变为化学性质稳定的二氧化硅晶体。提高酸浸渣有效硅含量的温度宜控制在140℃~400℃。 （6）正交试验结果表明：提高有效硅含量的最佳工艺条件为在酸浸渣中加入助剂KOH于200℃温度下焙烧6h，有效硅含量可达25.62%，比未处理的酸浸渣有效硅含量(3.62%)提高了6.1倍；比原始镁还原渣的有效硅含量(4.35%)提高了4.9倍。 （7）利用氨水控制pH可分离滤液中的三价铁元素，除铁率约为76%。
[Abstract]:Magnesium reduction slag is an industrial waste produced by silicon thermal reduction process for magnesium smelting. The main components of magnesium reduction slag are SiO2,CaO and MgO.. Smelting magnesium by silicon thermal reduction method belongs to high energy consumption and high pollution industry. The production of 1t raw magnesium requires 11t dolomite, about 10t coal, 1.2t ferrosilicon, and at the same time releases 35t CO2 gas and 0.2t SO2 gas to produce about 7t mg reduction slag. In 2014, the production of 1t raw magnesium requires 11t dolomite, 10t coal and 1.2t ferrosilicon. The output of raw magnesium in China is eight hundred and seventy three thousand seven hundred and ninety nine tons, and more than 6 million tons of magnesium reduction slag is produced. Magnesium reduction slag is easy to be powdered, hydrated solution is alkaline, and the environment is seriously polluted. With the massive discharge and accumulation of magnesium reduction slag, not only a lot of resources are lost, but also a lot of land resources are taken up, and the landform and vegetation are destroyed. Magnesium reduction residue has caused great influence on crops and surrounding environment with Rain Water's flushing into rivers and lakes, which seriously endangers human health and the growth of crops. At the same time, mg reduction residue contains rich nutrient elements in soil, but can not be directly absorbed by crops. In order to solve the above problems, the feasibility of preparing silicon calcium magnesium compound fertilizer from magnesium reducing slag was studied firstly, and then the increase of available silicon content in magnesium reduction slag was studied, and XRD,SEM, was used to study the feasibility of preparing silicon calcium magnesium compound fertilizer from magnesium reducing slag. The experimental results and mechanism were analyzed by UV spectra. The results showed that: (1) on the basis of consulting a large number of literatures and combining with the physical and chemical properties of magnesium reducing slag, the process of preparing Si-Ca-mg compound fertilizer from mg-reducing slag was preliminarily worked out. (2) the reduced slag contains Si-Ca-mg elements required for crops, its components can meet the basic elements and contents of Si-Ca-mg compound fertilizer, and the content of heavy metal elements is very small, which can meet the basic requirements of preparation of Si-Ca-mg compound fertilizer. (3) after calcination of magnesium reducing slag with quartz sand, the phase transition occurs. The conversion from Ca2SiO4 with low reaction activity to CaSiO3, with higher reaction activity is propitious to dissolve with hydrochloric acid. When adding 13.53% quartz sand, that is, the content of SiO2 in magnesium reducing slag is up to 43%, the minimum calcination temperature is 1460 鈩
本文编号：2447206
[Abstract]:Magnesium reduction slag is an industrial waste produced by silicon thermal reduction process for magnesium smelting. The main components of magnesium reduction slag are SiO2,CaO and MgO.. Smelting magnesium by silicon thermal reduction method belongs to high energy consumption and high pollution industry. The production of 1t raw magnesium requires 11t dolomite, about 10t coal, 1.2t ferrosilicon, and at the same time releases 35t CO2 gas and 0.2t SO2 gas to produce about 7t mg reduction slag. In 2014, the production of 1t raw magnesium requires 11t dolomite, 10t coal and 1.2t ferrosilicon. The output of raw magnesium in China is eight hundred and seventy three thousand seven hundred and ninety nine tons, and more than 6 million tons of magnesium reduction slag is produced. Magnesium reduction slag is easy to be powdered, hydrated solution is alkaline, and the environment is seriously polluted. With the massive discharge and accumulation of magnesium reduction slag, not only a lot of resources are lost, but also a lot of land resources are taken up, and the landform and vegetation are destroyed. Magnesium reduction residue has caused great influence on crops and surrounding environment with Rain Water's flushing into rivers and lakes, which seriously endangers human health and the growth of crops. At the same time, mg reduction residue contains rich nutrient elements in soil, but can not be directly absorbed by crops. In order to solve the above problems, the feasibility of preparing silicon calcium magnesium compound fertilizer from magnesium reducing slag was studied firstly, and then the increase of available silicon content in magnesium reduction slag was studied, and XRD,SEM, was used to study the feasibility of preparing silicon calcium magnesium compound fertilizer from magnesium reducing slag. The experimental results and mechanism were analyzed by UV spectra. The results showed that: (1) on the basis of consulting a large number of literatures and combining with the physical and chemical properties of magnesium reducing slag, the process of preparing Si-Ca-mg compound fertilizer from mg-reducing slag was preliminarily worked out. (2) the reduced slag contains Si-Ca-mg elements required for crops, its components can meet the basic elements and contents of Si-Ca-mg compound fertilizer, and the content of heavy metal elements is very small, which can meet the basic requirements of preparation of Si-Ca-mg compound fertilizer. (3) after calcination of magnesium reducing slag with quartz sand, the phase transition occurs. The conversion from Ca2SiO4 with low reaction activity to CaSiO3, with higher reaction activity is propitious to dissolve with hydrochloric acid. When adding 13.53% quartz sand, that is, the content of SiO2 in magnesium reducing slag is up to 43%, the minimum calcination temperature is 1460 鈩
本文编号：2447206
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