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排序方式: 共有335条查询结果,搜索用时 31 毫秒
91.
利用粉煤灰改进含铜酸性废水硫化法处理工艺 总被引:2,自引:0,他引:2
用粉煤灰对硫化沉淀法处理含铜酸性废水工艺进行改进试验,试验表明粉煤灰有吸附和絮凝沉降的作用,可显著改善单一硫化法沉降速度慢和脱水困难的缺陷。 相似文献
92.
Ionela Birloaga Vasile Coman Bernd Kopacek Francesco Vegliò 《Waste management (New York, N.Y.)》2014,34(12):2581-2586
This study refers to two chemical leaching systems for the base and precious metals extraction from waste printed circuit boards (WPCBs); sulfuric acid with hydrogen peroxide have been used for the first group of metals, meantime thiourea with the ferric ion in sulfuric acid medium were employed for the second one. The cementation process with zinc, copper and iron metal powders was attempted for solutions purification. The effects of hydrogen peroxide volume in rapport with sulfuric acid concentration and temperature were evaluated for oxidative leaching process. 2 M H2SO4 (98% w/v), 5% H2O2, 25 °C, 1/10 S/L ratio and 200 rpm were founded as optimal conditions for Cu extraction. Thiourea acid leaching process, performed on the solid filtrate obtained after three oxidative leaching steps, was carried out with 20 g/L of CS(NH2)2, 6 g/L of Fe3+, 0.5 M H2SO4, The cross-leaching method was applied by reusing of thiourea liquid suspension and immersing 5 g/L of this reagent for each other experiment material of leaching. This procedure has lead to the doubling and, respectively, tripling, of gold and silver concentrations into solution. These results reveal a very efficient, promising and environmental friendly method for WPCBs processing. 相似文献
93.
R. Cayumil R. Khanna M. Ikram-Ul-Haq R. Rajarao A. Hill V. Sahajwalla 《Waste management (New York, N.Y.)》2014,34(10):1783-1792
The rapid consumption and obsolescence of electronics have resulted in e-waste being one of the fastest growing waste streams worldwide. Printed circuit boards (PCBs) are among the most complex e-waste, containing significant quantities of hazardous and toxic materials leading to high levels of pollution if landfilled or processed inappropriately. However, PCBs are also an important resource of metals including copper, tin, lead and precious metals; their recycling is appealing especially as the concentration of these metals in PCBs is considerably higher than in their ores. This article is focused on a novel approach to recover copper rich phases from waste PCBs. Crushed PCBs were heat treated at 1150 °C under argon gas flowing at 1 L/min into a horizontal tube furnace. Samples were placed into an alumina crucible and positioned in the cold zone of the furnace for 5 min to avoid thermal shock, and then pushed into the hot zone, with specimens exposed to high temperatures for 10 and 20 min. After treatment, residues were pulled back to the cold zone and kept there for 5 min to avoid thermal cracking and re-oxidation. This process resulted in the generation of a metallic phase in the form of droplets and a carbonaceous residue. The metallic phase was formed of copper-rich red droplets and tin-rich white droplets along with the presence of several precious metals. The carbonaceous residue was found to consist of slag and ~30% carbon. The process conditions led to the segregation of hazardous lead and tin clusters in the metallic phase. The heat treatment temperature was chosen to be above the melting point of copper; molten copper helped to concentrate metallic constituents and their separation from the carbonaceous residue and the slag. Inert atmosphere prevented the re-oxidation of metals and the loss of carbon in the gaseous fraction. Recycling e-waste is expected to lead to enhanced metal recovery, conserving natural resources and providing an environmentally sustainable solution to the management of waste products. 相似文献
94.
Study on the mechanism of copper–ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal 总被引:1,自引:0,他引:1
Cong Peng Liyuan ChaiChongjian Tang Xiaobo MinYuxia Song Chengshan DuanCheng Yu 《环境科学学报(英文版)》2017,29(1):222-233
Heavy metals and ammonia are difficult to remove from wastewater, as they easily combine into refractory complexes. The struvite formation method (SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia. The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper–ammonia complex ion. Ammonia was separated from solution as crystalline struvite, and the copper mainly co-precipitated as copper hydroxide together with struvite. Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide. Hydrogen bonding was concluded to be the key factor leading to the co-precipitation. In addition, incorporation of copper ions into the struvite crystal also occurred during the treatment process. 相似文献
95.
Paul Hallwood 《Resources Policy》1985,11(3):191-200
This paper uses a model of the optimum buffer stock as a ‘filter rule’ together with a financial model that can be used to assess the efficiency of international commodity markets. The approach is simpler to apply than many other methods which have hitherto been used and yields an economy in theoretical and computational effort. The arguments are applied as a case study to the international copper market. The main conclusion is that private storage is not under-provided for and that a public buffer stock agency would be unlikely to be self-financing. 相似文献
96.
S.C. Ray 《Resources Policy》1984,10(2):125-133
The availability of mineral resources plays an important role in India's national economy. Copper, one of the important non-ferrous metals, has various industrial uses and demand for it is increasing in India where the inventory and production of copper, though not comparable with developed countries, shows an impressive growth rate, particularly during the last decade. With an increasing rate of industrial production envisaged in future plans copper consumption is expected to rise. Logistic curves have been used to study the potential long-term production capability under the dynamic concept of reserves and resources, with curves drawn for various estimates of total available resources. The production figures shown are not final and are subject to change due to a number of factors. This approach merely provides a method for projecting trends in future production. 相似文献
97.
98.
为研究仪器法和化学法对滤毒罐苯防护时间结果的一致性以及对防护时间判定的影响因素,参照强制性国家标准《呼吸防护 自吸过滤式防毒面具》(GB 2890—2009),通过选择不同的实验条件,测试4种不同滤毒罐对苯的防护时间,并对实验结果进行显著性差异检验和分析。结果表明:仪器法测定的防护时间小于化学法测定的防护时间;2种检测方法所测定的防护时间结果有显著性差异;测试浓度越高、气流流量越大、采样流量越大,2种方法测定防护时间的绝对差值越小。从防毒面具的安全性和与国外标准一致性考虑,建议采用仪器法判定防护时间。 相似文献
99.
In this work the development of a process for the recovery of copper from contaminated industrial soils is presented. Experimental tests on a standard soil contaminated with a solution of copper chloride were carried out. The metal was extracted from the contaminated soil by flushing with a 0.1 M aqueous solution of an ethylenediaminetetraacetic acid (EDTA) sodium salt. A maximum copper extraction efficiency of about 60% was observed. Copper was then separated from the extracted solution by precipitation with sodium hydroxide after addition of ferric sulfate. 相似文献
100.
Combustion experiments in a laboratory-scale fluidized-bed reactor were conducted to elucidate the effects of copper chloride as a catalyst on polychlorinated dibenzo-p-dioxins (PCDDs) formation in municipal waste incineration. We used model wastes with and without copper chloride (CuCl2 · 2H2O), both of which contained polyvinyl chloride as a chlorine source. Combustion temperature was set to 900 °C, and the amount of air supplied was twice the stoichiometric ratio. The experimental setup was carefully planned to suppress the influences of experimental conditions except the waste composition. Results of these experiments showed that copper chloride in the waste increased the amount of PCDDs formed and made the homologue profile to shift towards the highly chlorinated species. Copper chloride contributes to the PCDDs formation by promoting chlorination, whereby the reaction is important in that organic matter is chlorinated directly by copper compounds. Copper chloride did not exert a great influence on the isomer distribution patterns of PCDDs, while there appeared a significant difference in the case of PCDFs. This points out the difference of the major formation mechanisms between PCDDs and PCDFs. PCDDs are less formed by the catalytic reactions from carbon/polycyclic aromatic hydrocarbons than PCDFs in our experimental conditions. 相似文献