废物水泥窑共处置产品中重金属的释放特性

选用欧盟固体中无机组分有效量测试方法(EA NEN7371)和块状材料中无机组分的扩散实验方法(EA NEN7375),研究了模拟混凝土样品中重金属(Cr、Ni、As、Cd和Pb)的释放特性.结果表明,混凝土中重金属的有效释放量低于总量;不同重金属的有效释放量与总量比值差异较大.扩散控制是混凝土中Cr、Ni和Cd释放的主要机理,释放曲线与斜率为0.5的直线拟合较佳,且不同区间浸出量曲线的斜率均在0.35~0.65范围内;As在释放前期有延滞现象,但中后期仍以扩散控制为主;Pb的释放为溶解控制,受浸取液的pH值影响较大.重金属扩散系数负对数值按Pb相似文献   

某矿低铜废石综合回收利用项目职业病危害预评价

为了对某矿业有限公司低铜废石综合回收利用项目可能产生的职业病危害因素进行辨识、分析和评价,采用检查表、类比法相结合的原则对该项目的铲装、破碎、运输、筑堆等工艺进行分析评价,并利用经验法对浸出、萃取电积工艺进行分析评价。结果表明:类比工程中绝大部分粉尘、噪声检测点的浓（强）度符合国家标准;化学毒物、工频电场接触浓（强）度符合国家标准;电积车间的通风满足要求;萃取车间的事故通风能力不足。评价方法及通风计算方法对同类项目具有借鉴意义。     

电解锰渣中锰的浸出条件及特征

采用水洗-酸解法回收电解锰渣中锰,探讨了清水量、酸量以及温度在不同阶段对锰浸(洗)出条件的影响,分析了回收锰的主要因素及浸出特征。实验结果表明,50 g电解锰渣经m渣∶m水=1∶10的清水水洗后,采用10%的硫酸在70℃的水浴温度下酸解2 h,Mn2+浸出量为1.673 g,回收率达到97.3%,而温度和酸度对锰离子的浸出影响明显,酸度调控可有效分离酸浸锰液中金属成分,为减少电解锰渣环境污染的同时,实现电解锰渣资源化利用。     

A Review of Waste Tyre Utilisation in the Marine Environment

Waste tyres pose a major disposal problem on land creating a fire hazard and, in warmer climates, providing breeding pools for mosquitoes. the void space in tyres makes them unsuitable for land burial. Schemes to use shredded tyres for road bases and asphalt filler are being pursued in the USA. Tyre combustion for electricity production is being investigated in the UK.

The widespread availability and durability of tyres has led to their use in the marine environment for breakwaters/coastal defence structures and as artificial reefs for promoting fisheries.

Tyres have a low density and have been used in floating breakwaters. Schemes have been proposed to protect and strengthen shorelines with tyre structures.

The void space in tyres facilitates the construction of artificial reefs to attract fish. the most intensive use is in the south west Pacific and Australia. Tyre surfaces are colonised by algae and a wide range of faunal species, including corals and shellfish. the wide acceptance of tyres as a suitable reef construction material appears to be based largely on these observations. Experience of initial poor deployment practices in the USA led to tyres washing ashore after storms and resulted in the banning or restriction of their use in coastal states of the USA. A review of the scientific literature has yielded limited information on the environmental impact of tyres and in particular the leaching of heavy metals and organic compounds from tyres into sea water.

Preliminary results of tyre dust/sea water leaching studies are presented. These identify zinc as the major leachate (totalling 10mg/tyre after 3 months). Diluted leachates have not shown significant effects of the growth of the phytoplankton Phaeodactylum and Isocrysis.

Further work to characterise the sea water leaching of tyre compounds is recommended.     

Competition of Hydrogen and Manganese Ions for Adsorption Sites in Sitka Spruce Litter

The competition of hydrogen and manganese ions for adsorption sites in Sitka spruce litter was investigated in a factorial design, simulated acid rain experiment, which involved leaching of litter with simulated throughfall solutions at three pH levels (5.3, 4.3 and 3.3) and three manganese concentrations (0 to 0.2 mg1^-1). the throughfall solution at the lowest pH was the most efficient in removing exchangeable manganese from litter. the manganese concentration in the leachates was approximately proportional to the hydrogen ion concentration in the simulated throughfall solution. Under field conditions, throughfall manganese concentration also naturally tends to increase as a consequence of enhanced foliar leaching of manganese in response to increasing precipitation acidity. the manganese concentration in the simulated throughfall also affected manganese concentration in the leachates, however, and contributed to a buildup of exchangeable manganese in litter, thus counteracting to some extent possible adverse effects of excess leaching due to increased throughfall acidity.     

Incorporating uncertainty in a chemical leaching assessment

Pesticide leaching models are being used to assist in the regulation and management of pesticides by indicating their potential for leaching to groundwater. Uncertainty in model input data is not, regrettably, included in most pesticide leaching assessments. In the work described here, we use logarithmic transformations of the attenuation factor (AF), a simple process-based index model, to represent uncertainty in a pesticide leaching assessment. Characterization of a wide range of pesticides as `leachers' or `non-leachers' for a specific Hawaii hydrogeological setting is facilitated by comparing the log-transformed AF, designated AFR, for each chemical with two reference chemicals for which leaching behavior in Hawaii is known. Defining a mean and uncertainty interval for the AFR index of each chemical being ranked provides a practical method of incorporating data uncertainty into a regulatory protocol.     

环境pH对香溪河流域磷矿废石释磷特性的影响

为了评价三峡库区香溪河流域内所堆存的磷矿废石对地表水体的磷污染风险,以香溪河支流高岚河流域内具有不同风化时间的6座磷矿废石堆体为研究对象,依据US EPA Method 1313所规定的实验方法,开展了9种不同pH(2.0~13.0)条件下磷矿废石磷素浸出特性的实验研究,探讨了液相环境pH对磷矿废石磷素浸出浓度的影响。结果表明:在酸性环境下磷矿废石的磷素浸出浓度与pH呈负相关关系;中性及碱性环境下的磷素浸出浓度总体上低于酸性条件,其大小与环境pH之间无显著关系存在,但在pH=10.5±0.5范围内存在小幅升高;自然条件下磷矿废石堆体内部的液相环境为弱碱性(pH=7.8~8.8),且不会受当地酸雨长期淋滤的影响,在此条件下6种磷矿废石的磷素平均浸出浓度为0.7 mg/L,超标率为33 %。因此,研究区内的磷矿废石堆体可以形成点源形式的磷污染。在香溪河库湾水体富氧化问题日趋严重的前提下,应考虑将流域内堆存的磷矿废石作为第II类一般工业固体废物进行妥善处置,以降低其对香溪河库湾水体环境的磷污染风险。     

酸浸出法回收冶金污泥中的有价金属

采用二次酸浸出的方法回收镍钴湿法冶金工业污泥中的有价金属。先采用水和硫酸作为浸出剂浸出Mg和Na,最佳工艺条件为浸出液的pH 7.5、浸出时间5 min、浸出剂体积与干污泥质量的比(ω)为10 mL/g。再采用硫酸作为浸出剂、焦亚硫酸钠作为还原剂进行二次酸浸,在硫酸与污泥质量比为1.3、焦亚硫酸钠与污泥质量比为0.3、ω为5 mL/g、浸出温度85℃、浸出时间20 min的最佳工艺条件下,Co、Ni、Cu、Mn和Zn的浸出率分别达92.45%、93.48%、89.52%、97.78%和94.79%。经XRD表征,浸出后污泥中未见原污泥中的矿物相,说明原污泥中的矿物几乎全部被溶解。     

应用GLEAMS模型评估我国东南地区农业小流域硝态氮的渗漏淋失

应用GLEAMS模型估算我国东南亚热带地区农业小流域硝态氮的渗漏淋失.在五川流域8种不同土地利用方式的农田中埋设渗漏监测装置,每月采集水样分析硝态氮含量.用2002年4-12月作物生长季节的实测数据进行模型校验的结果表明,模型对水稻田除外的其他土地利用方式下硝态氮渗漏淋失模拟效果较好.五川流域2002年硝态氮淋失模拟计算结果表明,不同土地利用方式下硝态氮淋失时空差异显著,全年渗漏量(以氮计)为4.64～38.39 kg·hm-2,流域面积加权平均为29.99 kg·hm-2.甘蔗地、香蕉地和蔬菜地的年硝态氮渗漏量最高,渗漏峰值一般出现在7-8月.降雨、土地利用和化肥施用等人类活动是影响硝态氮渗漏淋失的主要因素.     

蚯蚓活动对重金属在土柱中淋溶行为的影响

采用土柱淋溶方法,以溴离子为示踪离子,研究了蚯蚓活动形成的土壤大孔隙对铜和锌离子在土柱中迁移行为的影响.运用平衡和非平衡对流-弥散模型对溴离子和铜、锌离子在不同土柱中的穿透曲线进行拟合.结果表明,蚯蚓活动形成的蚯蚓孔能够产生明显的优势流现象,这种优势流极大地加快了重金属离子在土柱中垂直向下迁移的速度.非平衡对流-弥散模型能很好地预测溴离子和铜、锌离子在蚯蚓孔土柱中的流出趋势,而平衡对流-弥散模型适合于预测溶质在对照（匀质）土柱中的流出趋势.