氨法浸出锌冶金渣尘提锌工艺及动力学研究

锌冶金渣尘作为一种重要的锌二次资源,来源广、储量大、具有较高的综合回收利用价值。以NH₃-CH₃COONH₄-H₂O为浸出体系,考察粒度、反应时间、搅拌速度、液固比、总氨浓度、NH₃与NH₄⁺物质的量比和温度对锌浸出率的影响,结果表明：控制浸出温度为25 ℃、总氨浓度为5 mol/L、液固体积质量比为5 mL/g、n（NH₃）/n（NH₄⁺）=1:1、搅拌速度为300 r/min、浸出时间为60 min,在此条件下锌的浸出率可达84%。含锌冶金渣尘浸出动力学分析显示,浸出反应表观活化能为22.66 kJ/mol,锌浸出过程的浸出速率受固体膜层扩散及界面化学反应共同控制,并获得了浸出锌的动力学速率方程。     

废镉镍电池中镉的选择性浸出

对镉镍废电池进行了选择性浸出．首先将废电池粉碎、焙烧,使镉和镍转变成氧化物．分析了pH及温度对镉浸出过程的影响．结果表明,扩散为镉浸出过程的控制步骤,在稀硫酸中就可完全浸出,在同样条件下,镍的浸出很少．因此,可以选择性地浸出镉．     

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。     

皂化法合成硬脂酸钡,镉新工艺

将化学计量比的硬脂酸、氯化钡或硫酸镉溶液、部分烧碱溶液和适量水搅拌加热,然后慢慢加入余量的烧碱溶液,可合成得到高质量的硬脂酸钡或硬脂酸镉产品,与传统的复分解法工艺相比,新工艺显著提高了生产效率,降低了能耗。     

氨液浸出催化氧化制备硫酸铜晶体的方法探讨

探讨了氨液浸出催化氧化制备硫酸铜的方法，并从热力学，动力学等角度进行了分析，对其反应可能性进行了论证，从多方面对反应机理进行了探讨。同时，将氨液浸出法与高温焙烧法作了对比，对其工业生产可能性作了分析，在多次实验的基础上，得出了较为合理的工艺条件。     

循环流化床锅炉烟气湿式氨法脱硫新工艺

SO_2是造成大气污染的主要因素之一,为减少锅炉排放烟气中SO_2的含量,采用湿式氨法脱硫脱除烟气中的SO_2。实践证明,氨法烟气脱硫工艺达到以废治废的目的,脱硫前、后烟气中SO_2浓度分别为2 200和200 mg/m~3(标态),每年减少SO_2排放量3 738 t。脱硫过程中没有三废产生,不会造成新的二次污染,符合国家关于环保污染治理工程的要求。     

氨浸法制取活性氧化锌新工艺研究

通过该厂具体的生产实践,介绍一种新的生产活性氧化锌的工艺——氨浸法,该法用含氧化锌75%的原料,生产活性氧化锌,工艺简单,污染小。一、前言本研究是在中型试验的基础上进行的工业性扩大生产试验。     

循环流化床锅炉烟气湿式氨法脱硫新工艺

简要介绍锅炉烟气湿式氨法脱硫工艺原理、工艺流程及特点,说明氨法脱硫是环保的、经济的、可行的。     

螯合絮凝沉降法从含镉水中除镉的研究

以聚丙烯酰胺絮凝剂为骨架,以二乙烯三胺为接枝螯合基团,在甲醛参与下,依据Mannich反应,制得螯合基团接枝絮凝剂CFA。研究了CFA在模拟含镉废水中除镉的效率,结果表明,在pH5～8范围,絮凝剂用量为15mL／L的常温条件,经两级絮凝处理可将浓度为10mg／L的Cd2＋降至0．087mg／L,去除率达99．1％,能够满足各工业废水排放标准。     

用弗雷德盐去除土壤淋洗液中的镉

用模拟酸雨(pH=4)对高镉土壤(全镉为10.590 mg/kg)进行浸取。实验结果表明,模拟酸雨对土壤中镉的浸出率仅为其总镉的1%左右,但浸出液中镉的含量(0.108 mg/L)仍远高出GB 3838—2002地表水Ⅴ类水质的要求,也高于GB 18918—2002城镇污水处理厂污染物排放标准(<0.01 mg/L),必须予以处理。弗雷德盐是以聚合铝为主要原料人工合成的层状双羟合物,它能以同晶取代、吸附或共沉淀形式去除水体中的重金属镉离子。研究表明,土壤浸出液中大量的Al3+、Fe3+会影响弗雷德盐对淋洗液中镉的去除,但处理后的镉含量仍可达到GB 18918—2002城镇污水处理厂污染物排放标准。     

铜镉渣综合利用研究

利用铜、镉和锌氧化还原电位相差较大的原理,对铜镉渣有价金属进行了分离。结果表明,控制浸出温度为50 ℃、硫酸质量分数为17%、液固体积质量比为4 mL/g、浸出时间为2.5 h时,金属铜可以得到优先分离。采用二段逆向锌还原镉,一段采用连续加锌置换,锌粉加入量为理论量的90%,加锌时间控制在20 min左右,二段置换中锌加入量为理论量的1.2~1.3倍,溶液中99.6%的镉被除去。除镉后溶液除钴后,硫酸锌溶液能够满足电锌要求。     

The effect of long-term phosphatic fertiliser applications on the amounts and forms of cadmium in soils under pasture in New Zealand

This paper presents the results of an investigation into the rate of Cd accumulation and changes in forms of Cd in a soil that has been subjected to long-term superphosphate fertiliser application. Results indicate that there had been a significant accumulation of Cd in the soil during the past 44 years. On the high fertiliser treatment (376 kg superphosphate ha^-1 yr^-1), Cd was estimated to have accumulated at a rate of 7.8 g ha^-1 yr^-1. During the course of the trial, there was an increase in the proportion of Cd associated with exchangeable and soil organic matter fractions on the fertilised plots, which was related to a corresponding increase in soil organic carbon levels. Results also indicate that although there was a large proportion of added Cd associated with the organic fraction, the concentration of applied Cd occurring in the residual fraction was also substantial (i.e >25% of added Cd). In addition, an investigation into the effects of residence time of Cd in the soil indicated that there was a redistribution of Cd into less soluble forms with time (i.e. residual Cd), along with a decrease in total soil Cd concentrations. There was also evidence of movement of Cd down the soil profile in this irrigated soil. The implications of these results for Cd phytoavailability are discussed.     

Coupling of electrodialysis and leaching processes for removing of cadmium from phosphate ore

Phosphate rock is a valuable material that is used for the production of large phosphorus chemicals. However, this natural material usually contains some toxic elements such as cadmium (Cd). Cd is a non-nutritive metal regarded as harmful to both humans and the environment. The main toxic effects of Cd on human health are the kidney and renal cortex diseases. Other effects were observed on pulmonary, cardiovascular, and musculoskeletal systems, in addition to including Cd as a human carcinogen. In order to reduce the cadmium content in the phosphate ore, an original method was studied and consists of coupling both leaching and electrodialysis. The effects of process parameters, such as reaction time, nature, and concentration of the extracting agent, liquid/phosphate ore ratio, pH, temperature, and current density, were investigated. The obtained results show that the cadmium extraction from phosphate ore using simple batch leaching does not reduce the cadmium content to the required level. However, the application of leaching- electrodialysis coupled method at optimum current density of 10 mA cm^?2 increases the cadmium extraction efficiency up to 84.3%. This synergetic process could be applied to the treatment of phosphate ore containing cadmium.     

A novel method for extracting vanadium by low temperature sodium roasting from converter vanadium slag

Long-term high temperature in conventional vanadium extraction process would cause particles to be sintered and wrapped, thus reducing extraction efficiency of vanadium. Based on the purpose of directional conversion and process intensification, this work proposed a combination of low temperature sodium roasting and high efficiency selective oxidation leaching in vanadium extraction. The investigation of the reaction mechanism suggested that the structure of vanadium slag was changed by roasting, which also caused the fracture of spinel. The addition of MnO₂ promoted the directional oxidation of low-valent vanadium into high valence. It also found that Na₂S₂O₈ could oxidize low-valent vanadium effectively in leaching. The leaching efficiency of vanadium reached 87.74% under the optimum conditions, including a roasting temperature of 650 °C, a roasting time of 2.0 h, a molar ratio of sodium-to-vanadium of 0.6, a MnO₂ (roasting additive) dosage of 5 wt% and a Na₂S₂O₈ (leaching oxidant) dosage of 5 wt%. This percentage is 7.18% higher than that of direct roasting-and-leaching under the same conditions.     

盐酸法生产饲料级磷酸氢钙新工艺研究

针对目前中国化工企业盐酸法饲料级磷酸氢钙生产工艺存在的弊端，系统地研究了“去渣一段中和”新工艺。实验结果表明：稀盐酸用量和浸取反应时间是影响磷矿石中磷及含氟杂质溶出率的关键因素，活性硅和氯化钠用量对产品质量有重要影响。通过实验数据分析处理得出实验条件下的最佳工艺条件：每30g磷矿粉加入稀盐酸（HCl质量分数≤20％）1200mL，浸取反应时间120min，活性二氧化硅（以SiO2计）用量1．0g，氯化钠用量2．0g.在此条件下，产品中磷收率达95％以上，氟的去除率达96％以上，产品质量超过HG2636-2000标准要求，生产成本下降。     

碱熔法提铝的工艺研究

对用碱熔法从明矾石中提取铝进行了实验。通过研究不同温度,摩尔比及反应时间对Al2O3转化率的影响摸索出碱熔提铝的最佳工艺条件。     

New method for extracting fracture toughness of ceramic materials by instrumented indentation test with Berkovich indenter

Applying finite element analysis, a method is proposed for evaluating fracture toughness of ceramic materials by instrumented indentation with Berkovich indenter. The crack-tip K_I (Stress intensity factor) of Berkovich-produced crack is numerically calculated by using virtual crack closure technique, in particular, three kinds of crack pattern, i.e., radial crack, transition crack and half-penny crack are identified and their crack fronts meet the equi-K_I requirement. The validity of the proposed method is verified by instrumented indentation tests on standard SRM2100 (Si₃N₄) and CRM156 (Fused Silica) samples. Comparison with six representative conventional indentation methods indicates that the proposed method has advantages including wide application range, high accuracy and applicability to different crack patterns. Additionally, it’s revealed that the conventional indentation fracture toughness formulae derived from Lawn-Evans-Marshall formula tend to exhibit larger test error when applied to materials of relatively high indentation work ratio W_e/W_t.     

辣椒红色素提取工艺可视化分析

以干红辣椒为原料,用丙酮作为溶剂提取辣椒红色素,运用均匀设计法设计实验,采用可视分析方法分析实验数据,得到提取高品质的辣椒红色素的最佳工艺范围为:提取温度75~85℃,提取时间270~360 min,固液比为30~40 mL/g。