制酸废水中汞的脱除工艺研究

采用研发的一种创新化学配方的新型脱汞剂,通过化学反应与汞结合,有效回收含汞酸性废水中的汞资源。当反应温度为室温、反应时间为25 min、脱汞剂/汞质量比为0.78、搅拌速率150 r/min,汞提取率高达99.9%以上,处理后液汞浓度降至0.03 mg/L以下。新型脱汞剂具有较高选择性,很难与As、Cd、Zn等其它重金属离子发生反应。     

铜冶炼制酸酸泥中汞富集试验研究

采用常压浸出—还原富集的方法,以次氯酸钠与硝酸为混合浸出剂,将铜冶炼酸泥中的汞转化为Hg2+转移至浸出液中,再将其还原富集为零价汞而分离。结果表明,铜酸泥中汞浸出的最佳条件为:液固比5mL/g、搅拌速度500r/min、浸出温度20℃、浸出时间30min、浸出液硝酸与次氯酸钠体积比4∶1,铜酸泥中汞浸出率可达93.6%。在浸出液中添加0.1%浓度为10%的次亚磷酸钠,絮凝沉降后,富汞渣中汞品位高达20.6%,达到制汞原料的需求,实现了酸泥中汞的净化与资源化。     

锌冶炼污酸汞的还原富集试验研究

采用Na PH2O2还原污酸中汞的方法,通过将污酸中的离子汞还原为单质汞,絮凝富集后沉降分离,达到净化锌冶炼企业污酸中汞的目的。研究考察絮凝剂的种类、还原剂投加量、反应时间对汞还原富集效率的影响。结果表明:试验最佳条件为反应温度20℃、搅拌速度500 r/min、还原剂次亚磷酸钠的投加量0.075%、絮凝剂为APAM、添加量为0.01%,反应时间20 min;优化条件下的污酸中汞的富集效率最高可达98.8%。XPS分析表明富集渣中汞主要以单质和化合物存在,单质汞含量共占45.9%,汞的化合物主要为氧化汞和硫酸汞,共占49.5%,此外还检测到少量氯化汞。还原富集后的单质汞在环境中极不稳定,最终以化合物的形式存在。     

从铜阳极泥酸浸液中回收铜和碲试验研究

试验研究了从铜阳极泥酸浸液中回收铜和碲的方法,采用AD-100高效铜萃取剂进行萃取铜试验,分析了水相初始pH、相比、萃取剂浓度等对铜萃取的影响,得到最佳工艺,即初始pH2.5、A∶O为2∶1、萃取剂体积浓度为25%、振荡10min时铜的萃取率达92.62%;且萃取过程中每个Cu~(2+)与两个萃取剂分子结合形成AD_2Cu。以亚硫酸钠直接还原除铜后液中的碲,分析了Na_2SO_3添加量、反应温度、搅拌速度以及反应时间对碲还原的影响,得出最佳工艺:Na_2SO_3添加量为20g/L、反应温度90℃、搅拌速度400r/min、反应50min时碲的还原率可达99.48%,且碲以二氧化碲的形式得到回收。     

微波消解-氢化物发生原子荧光光谱法测定污泥中汞和砷

利用高压密闭微波消解技术消解样品, 建立了氧化物发生原子荧光光谱法测定污水处理厂污泥中汞和砷的方法。对消解酸和消解程序进行了优化, 同时讨论了硼氢化钾浓度对测定的影响。结果表明, 选用10 mL 硝酸-盐酸(4+6)可将0.25 g污泥样品消解完全;确定消解程序如下:消解功率为850 W, 发射率为80%, 第1步采用5 min内从室温升温至110 ℃, 保持5 min, 第2步采用10 min内继续升温至180 ℃, 保持20 min;在硼氢化钾浓度为20 g/L时进行测定, 效果最佳。汞和砷的方法检出限分别为0.001 6 mg/kg和0.002 2 mg/kg。方法应用于污泥样品中汞和砷的测定, 相对标准偏差(RSD, n=6)分别为2.7 %～3.8%和1.1%～2.0%, 汞和砷的加标回收率分别为96%～102%和98%～104%。方法应用于土壤标准样品GSS-25和GSS-26中汞和砷的测定, 结果与认定值一致, 汞和砷的RSD(n=6)分别为4.5%～7.4%和2.2%～2.4%。     

高磷鲕状赤铁矿酸浸脱磷动力学

在HSC6.0计算软件热力学分析的基础上,采用正交实验确定了高磷鲕状赤铁矿酸浸脱磷保铁的最佳工艺,并以最佳工艺为基础进行了酸浸过程中脱磷和铁损反应的动力学研究。热力学分析表明H_2SO_4为最佳酸浸用酸。正交实验得出最佳酸浸条件为:H+浓度为0.5mol/L的H_2SO_4溶液、酸浸时间40min、温度298K、液固比200mL∶14g、搅拌速度100r/min。在该条件下,脱磷率可达98.89%,铁损率仅为0.51%。通过SEM-EDS对酸浸前后高磷鮞状赤铁块矿试样分析表征得出:经H_2SO_4浸出后,磷灰石基本完全溶解,含铁矿相未发生明显反应。动力学分析显示:优化条件下,酸浸脱磷反应在298~328K内符合收缩未反应核模型,浸出过程主要受内扩散控制,表观活化能为11.24kJ/mol;铁损反应在298~328K内遵循收缩未反应核模型,浸出过程主要受化学反应控制,表观活化能为42.24kJ/mol。     

高压密封微波消解-氢化物发生原子荧光光谱法测定锰矿中砷和汞含量

使用硝酸、盐酸、氢氟酸体系在高压密封微波消解器中完全消解锰矿样品,采用顺序注射-氢化物发生原子荧光光谱法检测样品中砷、汞含量。讨论了微波消解酸体系及用量的选择,研究了硼氢化钾浓度、载气流量、屏蔽气流量、溶液酸介质、载流溶液、溶液酸碱比例、样品中的主要基体元素等因素对砷、汞检测的影响,并确立了适宜的检测条件。砷浓度在0～100μg/L范围内与荧光强度呈良好的线性关系,砷的检出限为0.02μg/L;汞浓度在0～10μg/L范围内与荧光强度呈良好的线性关系,汞的检出限为0.05μg/L。采用本方法检测锰矿中砷、汞,砷的回收率可达105%～112%,相对标准偏差小于2.5%;测汞回收率可达91%～110%,相对标准偏差小于4.4%。使用该法分析参考物质和实际样品,分析结果与认定值和其他方法测定值一致。     

汞尾矿同步高效浸出汞锑规律

汞尾矿是汞矿采选冶过程产生的一种危险废弃物,长期堆存对生态环境具有较大危害。另一方面,尾矿中含有的汞、锑也是有价金属。在汞尾矿无害化处理过程中,实现高价值汞、锑的回收,意义重大。开发了硫化钠溶液体系同步柱浸汞尾矿中汞锑新工艺,考察了关键工艺对汞和锑浸出率的影响,获得汞锑同步高效浸出的优化参数,明确了浸出液循环利用和汞锑浓度提升方案。结果表明,经过浸出液循环和二次浸出,汞尾矿中汞和锑浸出率分别可达到96.7%和69.2%,浸出液中汞和锑的浓度可达到22.8 g/L和10.0 g/L。      

钠化焙烧钛渣的酸浸动力学研究

研究了钠化焙烧—酸浸工艺制备高钛渣过程中酸浸动力学、酸浸溶出规律和溶出反应的控制步骤,探讨了反应温度、盐酸浓度、搅拌速度对钛转化率的影响。结果表明,在下述最优工艺条件下,钛转化率达93%,TiO2品位达98.68%:搅拌速度400r/min、液固比10∶1、酸浓度20%、110℃酸浸90min。钛渣焙烧产物酸浸过程受固体产物层的内扩散控制,钛渣酸浸过程符合收缩未反应核模型,表观活化能为11.37kJ/mol,浸出钛渣动力学方程为1+2(1-x)-3(1-x)~(2/3)=0.244exp[-11370/(RT)]t。     

沸腾焙烧烟灰浸出金、银、铜的研究

采用酸浸—氰化工艺从某沸腾焙烧烟灰中浸出金、银、铜。结果表明,较优工艺为:酸浸硫酸浓度1.0mol/L,液固比4∶1,反应温度90℃,反应时间4h,搅拌速度300r/min;氰化浸出反应液固比3∶1,氰化钠浓度0.2%,pH 10~11,反应时间48h,搅拌速度300r/min。此条件下,金、银、铜的浸出率分别为97.16%、79.98%、96.04%。     

Electron Beam Irradiation for Mercury Oxidation and Mercury Emissions Control

A variety of air pollution control strategies have been investigated to reduce mercury emissions from coal-fired sources. The most developed and deployed technologies are based on adsorption of mercury onto powdered activated carbon followed by carbon collection. Mercury oxidation over selective catalytic reduction catalysts followed by wet scrubbing is another potential technique, and tests suggest that emissions reductions of 20–80% are possible, but test results are variable and ultrahigh removal (95%+) is unusual. The objective of this study was to investigate the effectiveness of electron beam irradiation to oxidize mercury vapor, to improve mercury removal with wet scrubbers or wet electrostatic precipitators (ESPs). Metallic mercury vapor samples in air and other atmospheres were prepared at concentrations of approximately 16?μg/m3. Samples were electron irradiated at energy levels of 2.5–10 kGy, equivalent to 3.1–12.4?kJ/m3 stack gas. Results show that mercury oxidation rate was dependent on both the gaseous atmosphere composition and the irradiation energy level. At medium energy levels, approximately 98% of gaseous mercury vapor was readily oxidized. Electron beam irradiation demonstrated high levels of mercury oxidation at the bench scale, and the technology might help improve mercury removal in wet scrubbers or wet ESPs when employed as a primary or secondary mercury oxidation technique.     

韶关冶炼厂汞回收工艺及生产现状分析

介绍了碘络合吸收－电解除汞工艺在韶关冶炼厂的应用情况，并对目前存在的问题提出了解决措施。     

某复杂低汞硒渣富集分离回收硒汞试验

采用两次焙烧工艺从某复杂低汞硒渣中富集分离回收硒、汞。首先将该硒汞渣在不制粒情况下,800~850℃空白焙烧1.5h,99%以上的硒、汞挥发进入烟尘而富集,且焙烧渣中汞含量不足0.01%。富集硒、汞的烟尘与石灰(CaO加入量为理论值1.25倍)制粒后在650℃焙烧90 min,固硒率达到99.5%,汞脱除率达到99.41%。     

汞资源分布与有色冶炼行业除汞现状

有色冶炼行业是我国汞的主要排放源之一,目前如何降低有色冶炼烟气中汞污染排放控制已经成为研究的热点。介绍了冶炼行业矿石中汞的含量以及分布,从协同脱汞技术到专门脱汞技术对冶炼行业除汞现状做了总结,同时对冶炼烟气脱汞趋势进行了展望。     

Mercury poisoning in a dentist

We examined a dentist with chronic elemental mercury poisoning electrophysiologically. Motor conduction in the upper and lower limbs was normal. Sensory nerve action potentials in the ulnar and median nerves were normal, but could not be elicited in the superfical peroneal nerves. Conduction velocity of the sural nerves was normal, but the action potential amplitude was abnormal. Following treatment with penicillamine, sensory conductions in the lower limbs returned to normal.     

Mercury and dental amalgam fillings

During 1993-95 a total of 169 patients (112 women, 57 men) with a wide range of complaints associated with earlier or present amalgam fillings were seen by the "Dental Biomaterials Adverse Reaction Unit" in Norway. Most patients had amalgam fillings; 19 had removed all amalgam, and 14 were in the process of replacing the amalgam fillings with other materials. Predominant symptoms were of a subjective and general nature (96% of the patients). Muscle and joint pain, headache, dizziness and feeling exhausted comprised the most common symptoms. Intra-oral pathology was observed in 48%. There was a correlation between the amount of amalgam ("amalgam score") and urinary mercury. Those without amalgam fillings and significantly lower values (median = 1.6 micrograms mercury/g creatinine) than those with amalgam fillings (medians: with amalgam = 3.5 micrograms/g; with partial removal of amalgam = 2.7 micrograms/g). Overall, in the present group of patients, no statistically significant correlation seemed to exist between the type and number of subjective symptoms or objective findings and the urinary mercury. This would indicate therefore that there is no straightforward association between urinary mercury and symptoms in the present group of patients.     

Mercury Disposal via Sulfur Reactions

A high-shear blending technique for converting large volumes of elemental mercury into mercuric sulfides has been evaluated. The two basic forms of mercuric sulfide (cinnabar and metacinnabar) were prepared by triturating stoichiometric ratios of elemental mercury and sulfur. X-ray analysis and scanning electron microscope techniques confirm the existence of both forms of mercuric sulfide. These sulfides passed the Toxicity Characteristic Leaching Procedure test for mercury vapor-phase requirements and thus meet waste acceptance criteria for handling∕storage of low-level radioactively contaminated mercury. Black mercuric sulfide (metacinnabar) is the recommended target product in the conversion of mercury to mercuric sulfide, because it is easier and safer to produce. Zinc-mercury amalgams were also prepared and compared with the sulfides in terms of meeting processing and storage requirements for mercury mixed waste. Mercury loading for both forms of mercuric sulfide is significantly higher than mercury loading in a typical transition metal amalgam.     

Mercury Adsorption Properties of Sulfur-Impregnated Adsorbents

Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 μg?Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.