Markov chain modeling of the global technological lifetime of copper

Markov chain modeling is applied to the global anthropogenic copper cycle for the year 2000. The lifetime of copper varies from product to product and region to region, as well as through time. Assumptions of average lifetimes are therefore subject to a high degree of uncertainty. A large state transition table is created that encompasses the life-cycle stages of copper (mining, smelting, refining, fabrication, use, waste management, scrap, and final disposal), five end-uses (buildings, transportation, consumer products, electrical equipment, and machinery) in eight world regions, including trade at every stage. The system requires closure by mass balance, so all possible routes of copper trade and recycling are considered. Transitions between each pair of states are calculated using previous material flow analysis data. The main result is that an atom of copper is used 1.9 times by human society before it enters final disposal. Scaling by the lifetime of copper in each life-cycle stage in each region gives a total average technological lifetime of copper of 60 years. A sensitivity analysis is applied to the model in order to test the robustness of the results. Several scenarios are also considered: increasing the recycling rate in each region to 70%, applying European or North American in-use lifetimes to all regions, and increasing the share of the world copper cathode and scrap markets taken in by Asia to 50%. Several limitations of the Markov chain approach are discussed, as are the further research opportunities it affords.     

Energy transition under mineral constraints and recycling: A low-carbon supply peak

What are the implications of primary mineral constraints for the energy transition? Low-carbon energy production uses green capital, which requires primary minerals. We build on the seminal framework for the transition from a dirty to a clean energy in Golosov et al. (2014) to incorporate the role played by primary minerals and their potential recycling. We characterize the optimal paths of the energy transition under various mineral constraint scenarios. Mineral constraints limit the development of green energy in the long run: Low-carbon energy production eventually reaches a plateau. We run our simulations using copper as the limiting mineral and we allow for its full recycling. Even in the limiting case of a 100% recycling rate, after five to six decades green energy production is 50% lower than in the scenario with unlimited primary copper, and after 30 decades, GDP is 3–8% lower. In extension scenarios, we confirm that a longer life duration of green capital delays copper extraction and the green energy peak, whereas reduced recycling caps moves the peak in green energy production forward.     

库存理论与期货价格:基于沪铜合约的实证检验

库存理论是期货价格的重要解释依据之一。文章以中国上海期货交易所的阴极铜合约作为研究对象,通过建立利息调整基差(iab)与库存量之间的内在函数关系,对库存理论的主要含义进行了实证检验。结果基本上不支持库存理论的基本含义,甚至波动性的非对称特征都没有得到证实。由于受数据可得性的限制,所采用的数据单一、样本期短,这使作者无法排除数据缺陷影响研究结果的可能性。     

2,2＆#39;-联喹啉光度法测定铜磁铁矿中铜含量

铜磁铁矿样品用适宜比例的HCl、HNO3、HClO4、HF混合酸低温消解,待样品溶解完全后,在适宜酸度下,用抗坏血酸将Cu2＋还原为Cu＋,在N,N-二甲基甲酰胺的存在下,使Cu＋与2,2′-联喹啉络合生成可溶性的紫红色络合物,采用分光光度法于548 nm波长处测量其吸光度。实验中考察了酸度、试剂用量、显色时间、共存离子的干扰等实验条件的影响,在选定的实验条件下,铜的线性范围为0-8.0μg/mL,方法检出限为0.0028μg/mL。将该方法用于铜磁铁矿中铜的测定,分析结果与标准物质的标准值和原子吸收光谱法的测量值基本相符,相对标准偏差为0.78%-1.69%,表示该方法适用于高硫、高磷和富铜的磁铁矿中铜含量的测定。