Radiological Waste Processing for the Recovery of Silver through Cementation with Zinc Powder

Abstract

The recovery of silver from silver-thiosulphate-fixer solutions of radiological wastes has been studied by cementation in batch-stirred reactors using zinc powder as the cementing agent. Silver is efficiently recovered from the solutions. The silver recovery rate and the total silver recovery increased with pH. Metallic silver was the product for cementation in deoxygenated solutions at all pH studied. With non-deoxygenated solutions and at low pH values, metallic silver cemented first, followed by silver sulfide. At high pH values, metallic silver was the cementation product. Electrochemical reactions are proposed for the cementation process in the presence and absence of oxygen.     

Deep Purification of Zinc Ammoniacal Leaching Solution by Cementation with Zinc Dust

Deep purification of zinc ammoniacal leaching solution by cementation using zinc dust was studied.The effects of relative amount of metallic impurities,dosage of zinc dust,purification time,temperature,pH value and total ammonia concentration in the solution on the purification of the solution were investigated.The results indicate that total ammonia concentration in the solution had no effect on the purification,but relative amount of metallic impurities,dosage of zinc dust,purification time,temperature and pH value of the solution were the main factors influencing the purification.Keeping appropriate molar ratio of copper to cadmium or nickel to cadmium was beneficial to the cementation of cadmium.Nevertheless,the presence of cobalt went against the cementation of cadmium and cobalt.All metallic impurities could be decreased to acceptable levels under the optimized conditions of 2 g/L of zinc dust dosage,1 h of purification time,35℃,pH value 9.03 of zinc ammoniacal leaching solution.The deeply purified zinc ammoniacal solution obtained by one-stage purification meets the requirements of zinc electrowinning.     

低纯度氧化锌制备磷酸锌研究

研究了用低纯度氧化锌(96%)通过复合溶剂净化,同时将氧化锌转化为液相改变传统的固-液相反应为液-液反应制备磷酸锌的新工艺,考察了净化和液-液反应的有关的工艺条件,制备得到高纯度磷酸锌。     

浸锌溶液中多元金属离子使用消耗的研究

通过原子吸光度的标准曲线求出使用到不同阶段的浸锌溶液中Zn2 、N i2 、Fe3 、Cu2 的含量;在大量实验的基础上,通过测试浸锌溶液密度,总结出浸锌溶液密度与浸锌溶液颜色及消耗量之间的关系。研究表明:原子吸光度法可以精确计算各种金属离子的实际消耗,浸锌溶液密度监控法可以直观简明的表示浸锌溶液的消耗量。     

纳米ZnO制备过程中的热处理条件分析

采用均匀沉淀法制备纳米ZnO，研究了热处理条件对粒径的影响。通过TG－DTA，XRD的研究表明：老化时间越长，焙烧温度越高，焙烧时间越长，升温速率越慢得到的纳米粒子粒径越大。     

羟基磷灰石对水溶液中锌离子的吸附动力学研究

以废弃的鸡蛋壳为原料,制备了碳羟基磷灰石,用红外光谱对其结构进行了表征。将得到的碳羟基磷灰石进行水溶液中锌离子的吸附,考察了吸附过程的动力学,结果表明,碳羟基磷灰石对水溶液中锌离子的吸附符合二级反应动力学方程：1/ρR=0.0536t＋1.0992,相关系数R=0.99724,其拟合度比较好。     

纳米氧化锌的制备与微观组织分析

采用均匀沉淀法制备纳米氧化锌。讨论了反应物浓度、配比、表面活性剂种类和用量对粉体粒径及分散性的影响。结果表明,反应产物为纯的氧化锌,其微观组织相貌为纳米特征。     

Recovery of Copper from Leaching Solution of Copper Smelting Ash

An efficient and reliable approach based on solvent extraction to selectively recover copper from leaching solution of Jinchuan copper smelting ash has been developed in this work. And the extraction isotherm of 50%(j) N902 with initial aqueous acidity of 19.6 g/L was determined at 25℃. The results show that the extractant, N902, has good selectivity to copper, and its saturated capacity of copper under the given conditions is over 23 g/L. The recovery rate of copper in the extraction is over 99%. And copper extraction equilibrium is reached in 90 s using 50% N902 with kerosene as the diluenting agent at an organic and aqueous volume phase ratio (O/A) of 1. Furthermore, over 99.5% of the loaded copper in the organic phase could be stripped by applying 196 g/L H2SO4 as the stripping agent.     

活性纳米ZnO的制备

用成本低廉的锌焙砂为原料 ,通过直接沉淀法首先合成前驱物碱式碳酸锌 ,然后烘干分解得到活性纳米ZnO粉体。TG -DTA表明前驱物为碱式碳酸锌 ,XRD估测颗粒尺寸为 90nm ,产品气敏度为 17.8。     

用含锌烟尘制备活性氧化锌的工艺研究

以含锌烟尘为原料,用酸法制得了活性氧化锌,产品达部颁标准。考察了硫酸浓度、固液比、温度及时间对浸出率的影响。在优惠条件下,实验浸出率可达９８％左右。三段控温添加锌粉除杂以及氨水与碳酸氢铵复配作为沉淀剂是技术关键。     

回收锌制备氧化锌粉体的新工艺

回收含锌催化剂废料中的锌来制备氧化锌粉体。先用氯化铵浸取含锌催化剂,经过滤得到氯化锌溶液;滤液中加入碳酸氢铵反应得到白色沉淀,经过滤煅烧滤饼得到氧化锌粉体。单因素实验确定了制备氧化锌粉体的适宜工艺条件:浸出反应温度60℃,反应时间2 h,原料配比n(Zn2+)∶n(NH4+)=1∶2.2。滤液中加入的碳酸氢铵配料比n(Zn2+)∶n(NH4HCO3)=1∶2.3,反应时间1 h,抽滤得中间产物。中间产物煅烧温度为300℃,煅烧时间1 h。样品进行XRD表征,杂质峰比较少,与标准卡片参数基本一致,晶体结构较好。     

氨络合物法提纯次质氧化锌制活性氧化锌新工艺

报道了一种以质次氧化锌（ＺｎＯ６５─９０％）为原料，碳化氨水作浸取剂，用氨络合物法制取活性氧化锌的新工艺。     

铜离子在硫酸锌电解液深度净化除钴中的作用

对Cu2+在湿法炼锌浸出液锑盐法深度净化除钴过程中的作用进行了研究. 考察了钴离子浓度达到深度净化浓度([Co2+]<0.1 mg/L)的时间、低于该浓度的持续时间及所需初始铜离子浓度([Cu2+]0)等因素,综合衡量除钴效果,得到优化实验条件为：[Co2+]0=15 mg/L时,钴/锑质量比(Co/Sb)=2:1,[Cu2+]0=200 mg/L,达到深度净化浓度的时间和保持该浓度的时间分别是25和70 min;[Co2+]0=7.5 mg/L时,Co/Sb=2:1,[Cu2+]0=100 mg/L,达到和保持深度净化浓度的时间分别是40和55 min. 搅拌转速对除钴效果影响不大,高转速有利于钴返溶,返溶的原因可能是沉积的碱式钴盐溶解.     

乙二胺-水体系中合成氧化锌纳米带

以乙二胺为介质,采用溶剂热法,在乙二胺-水体系中合成出宽度为20~30 nm、长度为500~600 nm的氧化锌纳米带,并进行了表征. 在反应过程中,氧化锌纳米带通过"溶解-结晶"机制形成,溶剂乙二胺的配位是氧化锌纳米带形成的关键因素,通过调整NaOH用量控制溶液碱度,实现了氧化锌纳米带的取向生长.     

铜氨废水处理与废铜液回收

简述某电子厂生产电路板过程中产生的镀铜废液，废水回收处理方法，介绍应用高质量浓度含铜废液制取工业硫酸铜与海绵铜的工艺方法和流程，铜氨废水的处理要用破络添加混凝剂沉淀后可达标排放，对调试，运行中一般故障的排除进行了论述。     

Thermal Conductivity of Zinc Oxide: From Green to Sintered State

The thermal conductivity of ZnO with different particle sizes (micrometer, submicrometer, and nanometer) was measured using the laser flash technique. As the "green" samples were heated from room temperature to 600°C (and 1000°C) and then cooled down to room temperature, the thermal conductivity was measured in situ . A model for interparticle neck growth was developed based on mass transfer to the neck region of a powder as a result of known temperature. By combining this model with a three-dimensional numerical code, the thermal conductivity of ZnO was calculated. Excellent agreement between the theoretical calculation and experimental data was found.     

含铜硝酸退镀液中铜的回收和硝酸的再生

用草酸铜沉淀法回收含铜硝酸退镀液中的铜并再生硝酸。研究了草酸加入系数(n_(草酸)∶n_(铜))、反应时间及反应温度等对沉淀效果的影响。确定的最佳工艺条件为:Cu~(2+) 136.52g/L,草酸加入系数0.9,搅拌速率300r/min,28℃,60min。在此工艺条件下,铜的沉淀率约为90%,草酸残留率小于1%,草酸铜产品的纯度达到98.33%。     

锌冶炼渣浸出模拟液铁沉降试验研究

实验研究了不同反应条件的铁沉降效率及锌、镉损失率。结果表明,氧气做氧化剂pH为3.0~3.5时,反应7 h后,铁沉降效率不高,仅达到34%,锌、镉损失率随反应时间的增加而增加。铁沉降效率随pH及温度的升高而增大,SEM和XRD分析表明,pH为3.0时的沉铁渣中主要成分是针铁矿。     

聚乙二醇/氯化锌条件下回收CFRP方法研究

以真空辅助成型工艺(VARI)制作的碳纤维增强复合材料(CFRP)平板件为降解试件,使用乙酸对其进行分层预处理,然后以聚乙二醇为溶剂,氯化锌为催化剂,采用控制变量法在不同的反应温度、反应时间,氯化锌浓度等工艺参数下对CFRP进行降解回收。利用扫描电子显微镜、X射线光电子能谱仪、动态接触角测量仪、纤维强度仪对回收碳纤维的表面形貌和元素、浸润性以及力学性能进行表征分析。结果表明,CFRP降解的理想工艺条件为:用乙酸于120℃下分层预处理30 min,然后在190℃下,使用浓度为0.6 mol/L氯化锌/聚乙二醇环境反应60 min。使用该方法回收的CFRP,树脂降解率能达到98%以上,碳纤维表面干净光滑无树脂残留,表面元素与原丝相比变化较小,碳纤维和水与乙二醇的浸润性相比原丝得到改善,碳纤维的弹性模量达到原丝的98%以上,拉伸强度达到原丝的97%以上。     

硫酸锌溶液中混凝沉淀降氟实验研究

利用硫酸铝对硫酸锌电解液进行除氟实验研究。探讨了温度,反应时间,硫酸铝加入量和硫酸铝的投加方式等因素对除氟效果的影响。实验结果表明,当温度为30℃,反应时间20min,硫酸铝加人量至少为3g／L和硫酸铝的投加方式为先加硫酸铝再加氧化锌调pH时,氟的浓度可降至29．79mg／L,达到锌冶炼企业对电解液中氟含量要小于50mg／L以下的要求。