种植膜回收废糖水中的柠檬酸钙应用研究

阐述了用种植膜设备代替传统自然沉降法回收中和废糖水中柠檬酸钙,新方法克服了自然沉降法工艺所存在较多的缺点。该法自动化程度高,降低了生产成本,减轻了废水处理压力。

白泥回收轻钙的品质及对加填与施胶的影响

2011~2013年泰格林纸集团技术中心承担了＂十二五＂国家科技支撑计划课题《3万吨/年草浆碱回收白泥精制碳酸钙技术及示范》,课题参与单位有造纸工业生产力促进中心、华南理工大学、陕西科技大学。本文对课题中部分研究成果,结合岳纸白泥回收轻钙的生产实际进行归纳总结,提出了造纸填料的质量评价指标,指出了白泥回收轻钙的品质差异,分析了白泥回收轻钙对加填和施胶影响的机理。

钛石膏及废酸中“硫-钙”资源的高值化利用

硫酸法钛白粉副产的钛石膏和废硫酸的产量大、利用率低。介绍了两步法中和钛白酸性废水新工艺、磷酸络合脱钛和硫酸浓差结晶除铁新技术,解决了大量钛石膏堆存和钛白废酸资源利用两大问题,实现了其中硫、钙资源的高值化循环利用,产生了良好的社会效益、经济效益和环境效益。

氯化铵浸出镁还原渣提钙工艺

皮江法炼镁过程产生大量的镁还原渣,堆存过程中易造成土壤碱化和板结等环境问题,在消纳方面主要用于制备水泥、建筑砖和脱硫剂,综合利用价值低。基于此,提出氯化铵浸出镁还原渣工艺路线,该工艺可以提取和分离镁还原渣中的钙、硅等元素,使镁还原渣成为钙源和硅源,实现镁还原渣的零排放和高值化利用。现针对工艺中的浸出过程,研究在各单因素条件下钙的浸出率及浸出渣物相,得出以下结论:氯化铵能对镁还原渣中钙进行选择性浸出,其浸出率与反应温度、氯化铵浓度、液固体积质量比等密切相关;浸出率随氯化铵浓度、液固体积质量比的增大而增大,随温度的升高先增加后减小;较佳浸出工艺条件为反应温度25℃、氯化铵浓度15%、液固体积质量比40∶1,该条件下,钙的浸出率达到88.7%;浸出渣物相主要为氧化镁、碳酸钙、二氧化硅等物质,通过洗涤工序可以获得较为纯净的含硅原料。

高镁脱硫废水软化和镁回收实验与机理分析

随着《节约能源法》、《环境保护法》等一系列用水排水政策和法规的颁布,国内对污水、废水排放标准有了更严格的规定,这无疑使得脱硫废水深度处理研究热情进一步升温,而对废水的软化处理作为废水深度处理的一个必要环节就显得尤为重要。本文根据国内某火力发电厂三联箱前出水的脱硫废水水质特征,介绍了一种脱硫废水的软化方法,在三联箱处理废水的工艺基础上做了适当的改造,通过向脱硫废水加入碱液和碳化的方法介绍了废水软化和镁回收的实验。实验结果表明,去除重金属阶段、回收氢氧化镁阶段和碳化阶段分别将脱硫废水的pH调至8.8、10.2和8.5是比较合理的,处理后的脱硫废水既可以达到后续水处理单元的要求又可以最大程度的回收高品质的氢氧化镁。

陈旧颅骨的DNA检验

陈旧颅骨DNA含量低且降解严重,一直是法医DNA检验的难点之一。本文介绍了一种改善陈旧颅骨DNA检验效果的方法,在几起陈旧颅骨案件DNA检验中,从取材部位的选择、脱钙液浓缩与回收、大体系提取纯化等方面对DNA提取进行优化,成功获得常染色体和Y染色体STR多态性检验结果。结果表明:颞骨岩部可作为陈旧颅骨检验优选的取材部位,与颅骨其他部位相比成功率较高;此外,在骨粉脱钙环节,利用Amicon Ultra-1510K离心超滤管可去除脱钙液中大量的水分和离子等小分子,从而将大分子DNA截留回收,有效降低了DNA损耗量;另外,陈旧颅骨DNA质量较差,提高骨粉使用量、增加提取纯化体系也能明显提升DNA回收量。本方法提高了陈旧颅骨的DNA回收量和质量,可为后续类似陈旧骨骼、牙齿DNA检验提供借鉴。

Extraction of vanadium from molten vanadium bearing slag by oxidation with pure oxygen in the presence of CaO

A novel process of vanadium extraction from vanadium slag in its molten state was conducted at the laboratory scale by oxidation with pure oxygen in the presence of CaO. The effect of mass ratio of CaO to V2O5 on the recovery of vanadium was studied. The sintered samples were leached by H2SO4 solution and characterized by XRD, XPS, SEM and EDS techniques. Compared with the roasting process, the energy saving effect of the proposed process was also discussed. The results showed that vanadium-rich phases were formed and vanadium mainly existed in the forms of CaV2O5 and Ca2V2O7. The formation mechanism of calcium vanadates in the molten vanadium bearing slag was explained. The XRD and XPS results implied that there was a limit to the oxidation reaction of V(IV) to V(V) under the high temperatures even though oxygen-supply was sufficient. An increase in the CaO content led to an increase in the formation of Ca2V2O7. About 90%of the vanadium recovery was obtained under optimal experiment conditions (mass ratio of CaO to V2O5 of 0.6, particle size 120 to 150μm, leaching temperature 90 °C, leaching time 2 h, H2SO4 concentration 20%, liquid to solid ratio 5:1 mL/g, stirring speed 500 r/min). The energy of 1.85×106 kJ could be saved in every 1000 kg of vanadium bearing slag using the proposed process from the theoretical calculation results. Recovery of vanadium from the molten vanadium bearing slag and utilisation of its heat energy are important not only for saving metal resources, but also for energy saving and emission reduction.

Preparation of potassium salt with joint production of spherical calcium carbonate from sintering dust

Several physical and chemical detection methods were used to study the basic properties of sintering dust （ESP dust） collected from Baogang Steel Corporation. The result shows that the major constituents of the ESP dust are KCl, NaCl, Fe2O_3 and Fe3O_4. Water leaching experiment on the sintering dust shows that KCl in the ESP dust can be separated and recovered by water leaching and fractional crystallization. Component analysis of leaching solution indicates that the massive calcium sulfate in the leaching solution should be removed first in order to obtain the pure potassium salt. In order to provide theoretical guidance to inhibit the dissolution of calcium ions from the sintering dust, the water leaching experiment of ESP dust and the dissolution behavior of CaSO_4 in the potassium chloride, sodium chloride, potassium sulfate and their mixed salt solution were studied. It is found that, a lower liquid-solid ratio should be chosen in the leaching process to inhibit the dissolution of calcium sulfate dehydrate. Using sodium carbonate solution as a precipitating agent, the influences of the concentration of sodium carbonate solution, reaction temperature, stirring speed and equilibrium time on the preparation of the spherical calcium carbonate were studied. Spherical calcium carbonate with good dispersing performance and grain size distribution in nanometer range of less than 10 μm was obtained. Furthermore, a potassium recovery process with joint production of spherical calcium carbonate was designed. This process is technically viable and considerable in economic benefit.

Recovery of magnetite from FeSO_4·7H_2O waste slag by co-precipitation method with calcium hydroxide as precipitant

Proper utilization of the FeSO4·7H2O waste slag generated from TiO2 industry is an urgent need, and Fe3O4 particles are currently being widely used in the wastewater flocculation field. In this work, magnetite was recovered from ferrous sulphate by a novel co-precipitation method with calcium hydroxide as the precipitant. Under optimum conditions, the obtained spherical magnetite particles are well crystallized with a Fe304 purity of 88.78%, but apt to aggregate with a median particle size of 1.83 μm. Magnetic measurement reveals the obtained Fe304 particles are soft magnetic with a saturation magnetization of 81.73 A-m2/kg. In addition, a highly crystallized gypsum co-product is obtained in blocky or irregular shape. Predictably, this study would provide additional opportunities for future application of low-cost Fe3O4 particles in water treatment field.