【作者】 孙博；

【导师】 宁桂玲；

【作者基本信息】 大连理工大学 ， 化学工艺， 2007， 硕士

【摘要】 硼泥是生产硼砂产生的废弃物。其中主要含有氧化镁和二氧化硅，含有一定量的氧化铁、氧化铝，并含有少量的氧化硼、氧化钙、氧化锰等其他物质。每生产1吨硼砂要排放出4吨左右的硼泥。硼泥不仅占用土地，由于硼泥显碱性，对周围的耕地造成严重污染，影响硼加工企业的总体效益。随着我国硼工业的不断发展，对硼砂、硼酸的需求量逐年增大，硼泥的排放量也将逐年增加，造成了大量硼泥的堆积。仅对其中镁元素而言，硼泥的排放就是对宝贵镁资源的浪费。寻找适当的方法对硼泥中的镁加以综合回收利用，从而增加硼加工企业的总体效益，减少对环境的污染，目前已成为硼行业生产亟待解决的难题之一。氢氧化镁作为镁的一种重要无机盐化合物，用途十分广泛。尤其作为无机阻燃剂，它具有分解温度高、抑烟能力强、阻燃效果好、分解后不产生有毒有腐蚀性的物质等优点，近年来受到广泛的青睐，和众多科研人员的关注。本文以辽宁省大石桥市某硼砂厂产生的硼泥为原料，经酸浸提镁、除杂等过程得到镁盐溶液，以氨水作为沉淀剂，采用直接沉淀的方法合成阻燃级氢氧化镁。本文通过对比盐酸、硫酸、氯化铵饱和溶液的浸取效果而最终选择盐酸作为浸取剂；考察了镁浸取率的影响因素，从而确定了浸取过程的最优工艺。由于反应后的浸取液中剩有大量的盐酸，本文提出了一种浸取液循环使用工艺，即浸取液与盐酸组成协同浸取剂，多次参与循环。一次镁浸取率可达96.0％，平均浸镁率为90.68％。利用浸取液中各金属离子的水解pH值范围不同用氨水作沉淀剂进行除杂净化，得到精制的氯化镁溶液。并对除杂过程中产生的铁铝氢氧化物的回收作了初步探讨。以自制的氯化镁溶液为原料，氨水为沉淀剂，采用常温直接沉淀法合成了氢氧化镁。通过化学分析、X射线衍射(XRD)、透射电子显微镜(TEM)、热重分析、粒度分析、红外分析等多种分析手段，讨论了加料方式、反应温度、氨水浓度、氨水加入速度、反应终点pH值、陈化温度、陈化时间等因素水平对氢氧化镁的沉降性能、沉淀率等的影响，并初步探讨了分散剂对产品性能的影响。最终确定了最佳工艺条件。以4％的硬脂酸钠对氢氧化镁产品进行改性，改性后的产品粒度分布较为集中。产品纯度达到97.8％，完全可以满足阻燃需求。XRD分析也表明样品为纯净的氢氧化镁。热重分析表明样品的分解温度在350～450℃之间，450℃失水量为30.1％。TEM分析结果表明样品为针状，长径比为50左右。更多还原

【Abstract】 Boron slurry is the waste of borax manufacture. The main components of boron slurryare magnesium oxide and silica dioxide. It also contains some iron oxide and alumina oxide,and a small quantity of boron trioxide, calcium oxide and manganese dioxide. Every one tonborax manufacturing brings on four ton boron slurry emission. Boron slurry is not only theoccupation of land, but also produces severity contaminated to environment due to it’salkaline. This makes a negative influence on benefits of the factories. With the evolution ofboron industry and the growing demand of borax and boracic acid in China, the output ofboron slurry has been increased. This makes a large waste of the valuable magnesiumresources. It becomes urgent to be solved that to find a adequate method to recycle thevaluable magnesium resources.Magnesium hydroxide has widespread using as a kind of important inorganic salts.Especially as a kind of inorganic flame retardants, magnesium hydroxide has the advantage ofhigher decomposition temperature, strong smoke inhibition, fine flame-retardant effect andreleasing nonpoisonous and non-corrosive matter. It is highly interested by customers andscientific researchers in recent years. In this article flame-retardant magnesium hydroxide hasbeen prepared from boron slurry by two steps. At first magnesium chloride solution is gottenafter extraction of magnesium under acid leaching and separation of impurities. And then withthe precipitant ammonia water, flame-retardant magnesium hydroxide is synthesized by directprecipitation method.Hydrochloride acid is selected as the leaching agent by comparing the leaching effect ofhydrochloride acid, sulfate acid and ammonia chloride saturated solution through a greatnumber of experiments. The influential factors of magnesium leaching rate is investigated,and the optimal technical process is determined. The first-time magnesium leaching ratereaches to 96.0％and the average magnesium leaching rate is 90.68％. Impurity ions in theleaching solution, such as Fe³⁺, Al³⁺ and Mn⁴⁺, can be hydrolyzing to precipitate by ammoniadue to their different pH range of hydrolyzing. The synthesis and recycle of the iron-aluminum hydroxide complex has also been discussed preliminarily.Flame-retardant magnesium hydroxide has been prepared from self-made magnesiumchloride solution and ammonia water by direct precipitation method. The influence factors to the settling performance and precipitation rate of magnesium hydroxide, such as feedingmode, reaction temperature, concentration and adding speed of ammonia water, pH value atreaction end, ageing temperature and time and so on, have been discussed by the way ofchemical analysis, X-ray diffraction （XRD）, transmission electron microscope （TEM）,thermogravimetry analysis, grain size analysis, infrared analysis （IR） and so on. Effect ofdispersant on property of the product is discussed primarily. The optimal technical process isfinally determined. The product is modified by sodium stearate with the concentration of 4％.The grain-size distribution is from 600～1200 nm to 750～850 nm. The purity is around97.8％, which is fit for the need of flame-retardant. XRD analysis indicates product’s purity.TG analysis show that the decomposition temperature of product is between 350℃and 450℃, and water loss is 30.1％at 450℃. TEM analysis suggests that the product is needle-likewith the length diameter ratio around 50.更多还原