【作者】 黄小凤；

【导师】 宁平；

【作者基本信息】 昆明理工大学 ， 环境工程， 2013， 博士

【摘要】 磷化工是云南省的重要支柱产业之一,其中黄磷是最主要的创汇产品。随着人类社会需求的增加,黄磷生产的重要原料磷矿资源短缺现象日益严重,已被我国国土资源部列为“2010年后不能满足中国经济发展需求的矿种之一”。电炉法制磷生产过程产生大量含CO废气、含磷废水、磷铁、磷渣及泥磷,其中的泥磷是元素磷、粉尘杂质和水在冷凝过程中形成的性质稳定、难于分离的混合物,属于危险固体废物,必须没于水中存放,若处置不当,还易引起二次污染,泥磷的处置问题已成为了我国黄磷行业可持续发展的瓶颈。现有泥磷处理处置的方法很多,包括电炉制磷系统自身回收法、直接和间接法提取黄磷法等,在一定程度上回收了泥磷中的磷,但存在磷回收率低、未解决PH3二次污染问题。本文以氢氧化钠提取泥磷中的磷,得到产品磷酸盐(次磷酸钠及亚磷酸钠),同时采取提浓或转化为阻燃剂四羟甲基氯化磷(THPC)的方法,回收尾气中的磷化氢(PH3)。泥磷制备磷酸盐实验研究了反应温度、水磷比、碱磷比对产品得率的影响,确定适宜的操作条件：温度85℃、碱磷比4：1、水磷比110：1,此条件下反应时间6h、产品收率62.59%；采用结晶+乙醇蒸馏-重结晶法分离次磷酸钠和亚磷酸钠,考察乙醇浓度、乙醇用量、溶液pH、溶解温度、结晶温度、重结晶温度等影响因素,确定分离次磷酸钠、亚磷酸钠分离最适宜的条件：乙醇与原料用量比为1：1、浓度90%、溶液pH7.65、溶解、结晶、重结晶的温度分别为45℃、65℃、70℃,得到产品次磷酸钠、亚磷酸钠的纯度分别为98.75%、99.18%。PH3提浓实验研究了改性吸附剂5A分子筛的吸附性能,筛选了适宜的吸附剂,分别考察浸渍液浓度、干燥温度及焙烧温度、吸附流速及温度等对PH3净化效率的影响,通过正交实验,确定最适宜的条件：浸渍液NaCl浓度、干燥温度及焙烧温度分别为0.3mol/L、110℃及400℃,载气流速20mL/min、常温吸附,并对吸附剂的再生方法和性能进行了研究,确定适宜的再生条件：载气流速40mL/min、解吸温度为60℃。PH3与盐酸、甲醛合成THPC实验进行了催化剂的筛选,考察了空速、温度、原料配比及催化剂用量等对PH3转化率的影响,通过正交实验确定最适宜的合成工艺条件：以CuCl为催化剂,控制空速150h-1,温度60。C,催化剂用量0.5g,甲醛和盐酸摩尔比4：1,PH3转化率达到95%,符合工业商品THPC的要求。在此基础上,对各过程的机理进行分析。适宜条件下泥磷制取磷酸盐的动力学实验,表明磷生成次磷酸钠为一级放热反应,反应速率常数的方程式为：k=122.85exp(-37341/RT);结合结晶理论对次磷酸钠和亚磷酸钠分离过程的机理进行分析,确定溶液过饱和度是结晶过程的推动力。根据吸附等温线计算PH3吸附过程的吸附热及吸附量,根据吸附穿透曲线计算各温度条件下的吸附速率,结合吸附剂表征扫描电镜(SEM)、光电子能谱(XPS)结果,推断此吸附过程为物理吸附。通过宏观动力学研究,认为在催化剂作用下,PH3合成THPC的反应为一级反应。本文从黄磷工业危险废物泥磷中回收磷元素制备高附加值的化工产品次磷酸钠、亚磷酸钠,同时对反应尾气中的高浓度PH3回收利用,制备纯度较高的PH3或THPC,尽可能的回收泥磷中的有用资源,达到减量化的目的,研究称为可为泥磷清洁、无害化的处理处置提供理论基础。更多还原

【Abstract】 The phosphorous chemical industry is one of the major pillar industries of Yunnan province, which yellow phosphorous was the main export products as well as the key raw material of the chemical industry. With the increase of human consumption, the shortage of phosphate resources is worsening with the development and utilization of the phosphate. China’s Ministry of Land and Resources has set phosphate as one of minerals that it cannot meet China’s economic development demand after2010. A large quantity of waste gas containing a certain amount of CO, phosphorus wastewater, ferrophosphorus, phosphorus slag, phosphorus sludge produced during the production of phosphorus by electric furnace process, phosphorus sludge is a mixture of element phosphorus, dust and impurity, and water formed in condensing process, which has better stability and hard to separate. And it is a kind of dangerous solid wastes and must be stored in water, improper treatment can easily cause secondary pollution, so the treatment of phosphorus sludge become the bottleneck of the sustained development of phosphorous chemical industry. Many treatment methods have been developed, such as recovered by the system of electric furnace process, extraction of yellow phosphorus by direct and indirect methods, those methods could recovery phosphorous from phosphorus sludge to a certain extent, however, they led to a low recovery of phosphorous and secondary pollution from unprocessed PH3. In this thesis, phosphorous was extracted by sodium hydroxide from phosphorus sludge, and which was converted to phosphates (such as sodium hypophosphite, sodium phosphate), meanwhile, PH3in the off-gas was concentrated or it was converted to flame retardant tetrakis (hydroxyrnethyl) phosphonium chloride(THPC), then separation and purification was used to get the products with high addition value.Effects of reaction temperatures, alkali-phosphorus ratio and water-phosphorus ratio on the reaction were studied in the preparation of phosphate from phosphorus sludge, and the best reaction conditions were obtained, as following:reaction temperature at85℃, the ratio of alkali to phosphorus was4:1, the ratio of water to phosphorus was110:1. Under these conditions, the product yield of phosphates could reach62.59%within6h; a method of crystallization-ethanol distillation recrystallization was used to separate sodium hypophosphite from sodium phosphate, the influence laws of ethanol concentration, ethanol amount、pH value、solution temperature、crystallization temperature、recrystallization temperature on the purity of product were investigated. The results showed that optimal conditions were:the ratio of ethanol to material was1:1,ethanol concentration of90%, pH=7.65, the temperature of solution、crystallization、recrystallization were45℃,65℃,70℃respectively, under these conditions, the purity of sodium hypophosphite and sodium phosphate could reach98.75%,99.19%respectively. The absorption capacity and adsorption mechanism of5A molecular sieve for high concentration of PH3were investigated in PH3concentrating experiment. In order to get the suitable experimental conditions, the influence laws of impregnating solution concentration, drying temperature, calcinations temperature, gas flow rate and temperature on PH3absorption were investigated. The suitable adsorbent type and impregnating solution of active components were selected. The orthogonal experiment was used to verify the optimum experimental conditions. The results showed that optimal reaction conditions were:impregnating solution (NaCl) concentration of0.3mol.L-1、drying temperature of110℃、calcination temperature of300℃、gas flow rate of20mL.min-l and at normal temperature. The regeneration method and regeneration effect of adsorbents were researched, the most suitable regeneration method was obtained under the following conditions:gas flow rate of40mL.min-1and desorption temperature of60℃. PH3, hydrochloric acid, and formaldehyde were taken as materials to synthesis THPC, and the metal salt catalyst was selected during the process. Effects of space velocity, temperature, material ratio and dosage of catalyst on conversion efficiency of PH3were investigated. The orthogonal experiment was used to verify the optimum experimental conditions. The results showed that optimal reaction conditions were:CuCl acted as the optimal catalyst; space velocity of150h-1, reaction temperature of60℃, catalyst amount of0.5g, the molar ratio of formaldehyde to hydrochloric acid was4:1. Under these conditions, the conversion efficiency of PH3can reach95%, and the product could meet the industrial requirement.The mechanisms of these experimental were analyzed on above experiments. Under the suitable conditions, dynamic experiments and thermodynamic calculation were carried on at80℃,85℃and90℃. The results confirmed that the reaction was one stair exothermic reaction, and the reaction constant equation was calculated with the following equation:k=122.85exp (-37341/RT). The separation mechanism of sodium hypophosphite separated from sodium phosphate was analyzed depended on theory of crystal, and it showed that supersaturation degree was the impetus of crystallization process. The adsorption isotherm was used to calculate the adsorption heat of adsorption process, and the adsorption penetration curve was used to calculate the absorption rate of PH3under different temperatures. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the absorbent, combined with characterization results, which deduced that the adsorption process belonged to physical adsorption. In addition, the macroscopic dynamics of the synthesis of flame retardants THPC was researched, and the result showed that the reaction of synthetic flame retardants with catalyst was first-order reaction.In this paper, the utilization technology of phosphorus sludge was put forward, which reusing the phosphorus from phosphorus sludge to prepare high value-added chemical products such as sodium hypophosphite, sodium phosphate,high purity PH3or THPC, which can provide basic studies for phosphorus sludge disposal and harmless treatment.更多还原