烟化炉处理低品位锡中矿冷料工业实验

文章介绍了利用烟化炉硫化挥发处理低品位复杂锡中矿的工业实验。实验表明,烟化炉能顺利处理锡中矿,渣型合理,炉渣熔点较低;烟化炉处理锡中矿的锡挥发率为98.09%,直收率为94.09%,锡金属有较好的挥发率,金属在烟尘中的富集程度高,烟尘含锡达到47%,有利于锡的进一步回收,同时实验表明选冶结合的工艺可带来可观的经济效益。     

西藏某锑铅锌复杂多金属矿综合回收研究

复杂多金属矿分离回收是目前选矿面临的技术难题,也是解决资源短缺形势的有效手段。西藏某多金属矿有价元素为锑、铅、锌及伴生元素银,主要锑铅赋存矿物为脆硫锑铅矿,主要锌矿物为闪锌矿。矿石矿物组成复杂,有用矿物嵌布粒度细,共生紧密。针对该矿石性质,考虑经济技术指标,采用锑铅-锌优先浮选,阶段磨矿阶段选别的工艺流程,获得锑铅精矿锑品位30.31%、回收率90.76%,铅品位25.33%、回收率90.45%,银品位1899.40 g·t-1、回收率87.46%,锌精矿54.71%、回收率89.50%的选矿指标,此结果可作为该类矿石生产的技术依据。     

大厂难选老尾矿综合利用与生产实践

大厂矿区目前拥有3 000多万t的尾矿资源有待开发利用,这些尾砂矿的共性是结晶粒度微细,在-0.1 mm级别多数已单体解离,矿物表面深度氧化,有用金属分布粒度细微、含泥高、有残留药剂,＋1.0 mm级别的锡、铅、锌、硫铁紧密共生,选矿难度较大。广西华锡集团股份有限公司再生资源分公司通过与江西理工大学等多家科研院所联合技术攻关,采用选矿新技术、新工艺、新药剂,对处理矿石性质复杂难选的尾砂矿,取得了锡、铅、锑、锌金属回收率分别为38%、35%、32%和55%的选矿技术指标。     

采用真空炉处理粗锡与传统工艺对粗锡中锑砷含量经济临界点探索及工艺比较分析

文章分析了采用真空炉直接处理粗锡脱除铅铋及大部分砷锑的工艺,探索目前的氧化锅-结晶机传统工艺对租锡中锑砷含量的经济临界点,并对2种工艺的特点进行初步的比较和分析。     

三滩黄铁矿铅锌钼多金属矿资源综合回收选矿研究

三滩黄铁矿为中低温热液型及矽卡岩型,以黄铁矿为主,铅、锌、钼、硫化矿物共生的中型矿山。矿石主要有价非金属元素是硫,伴生有价金属元素是铅、锌、钼。矿山目前生产能力是300 t/d,选矿浮选回收硫精矿、铅精矿、锌精矿。为综合回收矿产资源,文章通过查明主要矿物组成、原矿物相分析及矿物嵌布特征,在现有优先浮选工艺的基础上制定合理的药剂制度及优化工艺流程,进行选矿试验,成功实现钼、铅、锌、硫综合回收并取得良好的选矿试验指标,为选矿厂合理开发利用该矿资源提供了选矿技术依据。     

广西有色金属工业路在何方——对广西有色金属行业创新的思考

广西是我国有色金属资源大省之一，目前已探明的铝、锡、铅、锌、铟、银、铜、钛、镉、铋、砷等金属的保有储量高达4200多万吨，许多稀、贵、重金属的保有量在全国乃至世界都占有极其重要位置。其中，铟储量居世界第一，锡储量全国第一，铝土、锑、锌储量都在全国前五位之内。2001年锡、锑、铟、氧化锌等金属产量分别占全国的42%、50.5%、52%、60%。因此，在广西“十五”规划中，有色金属工业列为5大产业支柱之首。然而，由于种种原因，广西有色金属工业整体仍处在粗放型经营的水平线上，表现在产业结构不合理，产品档次低，技术装备差；管…     

铝与铝的焊接方法

乡镇企业在开发铝制品或修配焊接铝部件时,有不少单位缺乏焊接技术,影响经济效益。今介绍两种有效的焊接方法。 1 焊药焊料焊接法 (1)焊药的配制 将70克硫酸锌溶解在100毫升水中,再加5毫升左右的氢氟酸搅拌均匀,装入塑料盒待用。 (2)焊料的制作 将100克锡、60克锌放在铁勺里熔化后,再加入40克镉熔化,搅匀后铸成细条焊料。 (3)焊接工序 将铝件表面氧化层用刀刮净,立即将铝件浸入焊药中晃动10—30秒,使铝呈灰色后取出,     

铅污染的原因与预防

随着生活水平的提高，人们越来越重视环境保护和食品安全。铅是污染物中毒性很大的一种重金属元素，它呈现灰白色、质软，切削面有光泽，在空气中则能迅速氧化而成为铅色。加热则能与卤素、硫、硒等反应，原子价有2价和4价，铅化合物中2价比4价稳定。粉末铅的火灾危险性为中度，其物理性质见表1：     

锡矿

一、矿物原料特点 锡是一种银白色金属，具强光泽，相对密度为7．0，熔点低（230℃），硬度为3．75，质软延展性好。锡在地壳中含量仅2×10^-6～3×10^-6。锡属于亲铜元素组，但在岩石圈上部又具有亲氧和亲硫的两性特征。锡与硫起作用时形成两种化合物：一硫化锡和二硫化锡，它们在高温下具有较强的挥发性。锡与氧也能化合，产生一氧化锡和二氧化锡。虽然锡具有二价和四价两种价态，但在自然条件下，四价化合物较为稳定，尤其是氧化锡（SnO2），它是地壳上最稳定的化合物之一。     

浅谈锌基合金电镀

锌基合金材质零配件具有力学性能高、摩擦性能优良、耐磨性能好、无火花和无磁性等特点,可以代替价格较贵的(锡、铝)青铜和(铅)黄铜等铜合金以及巴氏合金等制造轴瓦、轴套、蜗轮、滑块和丝母等耐磨减摩零件。由于锌基合金具有原材料价格低廉、熔化耗能少、熔烧无污染,对成形方法适应性广和切削加工性好等一系列优点,因而,采用锌基合金制造耐磨和减摩零件有着巨大的经济效益和社会效益。我国锌资源丰富,储量占世界总储量的三分之一,居世界第一位,具有发展锌基合金得天独厚的优势。     

Youth minimum wage reform and the labour market in New Zealand

This paper analyses the effects of a large reform in the minimum wages affecting youth workers in New Zealand since 2001. Prior to this reform, a youth minimum wage, applying to 16–19 year-olds, was set at 60% of the adult minimum. The reform had two components. First, it lowered the eligible age for the adult minimum wage from 20 to 18 years, and resulted in a 69% increase in the minimum wage for 18 and 19 year-olds. Second, the reform raised the youth minimum wage in two annual steps from 60% to 80% of the adult minimum, and resulted in a 41% increase in the minimum wage for 16 and 17 year-olds over a two-year period. We estimate the impact of this reform by comparing average outcomes for these two groups of teenagers, before and after the change, to those for 20–25 year-olds, who were unaffected by the reform. We find no evidence of adverse effects on youth employment immediately following the reform, but some weak evidence of employment loss by 2003. We also find evidence of a 10–20% increase in hours worked following the reform for employed 16–17 year-olds, and up to a 10% increase for employed 18–19 year-olds, depending on the specification adopted. Combined, wage, hours, and employment changes lead to significant increases in labour earnings and total income of teenagers relative to young adults. However, we also find evidence of a decline in educational enrolment, and an increase in unemployment, inactivity, and benefit receipt rates, suggesting that while the minimum wage reform increased the labour supply of teenagers, this increase was not matched by as large an increase in employment.     

金银花挥发油提取工艺研究

目的:采用蒸馏法提取,比较提取金银花中的挥发油,筛选出金银花中挥发油最佳提取方法。方法:取金银花进行加工处理,采用共水蒸馏法和通水蒸气蒸馏法提取其中的挥发油。结果:以芳樟醇为考察指标,结果显示,经盐加工处理后的金银花采用以上2种蒸馏法能提出淡黄色芳香的挥发油,较未经加工处理的金银花提取的芳樟醇含量多。结论:在提取金银花中挥发油的过程中,应经盐加工处理后再进行共水蒸馏提取。     

How the baby boomers' retirement wave distorts model‐based output gap estimates

This paper illustrates, based on an example, the importance of consistency between empirical measurement and the concept of variables in estimated macroeconomic models. Since standard New Keynesian models do not account for demographic trends and sectoral shifts, I propose adjusting hours worked per capita used to estimate such models accordingly to enhance the consistency between the data and the model. Without this adjustment, low‐frequency shifts in hours lead to unreasonable trends in the output gap, caused by the close link between hours and the output gap in such models. The retirement wave of baby boomers, for example, lowers US aggregate hours per capita, which leads to erroneous permanently negative output gap estimates following the Great Recession. After correcting hours for changes in the age composition, the estimated output gap closes gradually instead following the years after the Great Recession.     

Testing the intertemporal labor supply model: are jobs important?

The neoclassical life-cycle labor supply model assumes that hours of work are determined by labor supply choices alone and does not include a role for employers or job distinctions. An alternative model in which employers have an interest in employee hours and changing jobs is costly may reconcile weak and conflicting evidence regarding the neoclassical model. An important implication of such an alternative is that individuals may face hours constraints on a job and thus can choose hours freely only between jobs. This paper tests several implications of the neoclassical model against this alternative model of hours determination. Using a unique panel of individuals and jobs constructed using data on women from the 1988–1992 Panel Study of Income Dynamics, I compare hours variances and labor supply elasticities measured within and between jobs. Results provide some evidence against the neoclassical model and suggest that ignoring the role of employers in determining hours of work can lead to downward bias in estimates of labor supply elasticities.     

Online adaptive lasso estimation in vector autoregressive models for high dimensional wind power forecasting

Wind power forecasts with lead times of up to a few hours are essential to the optimal and economical operation of power systems and markets. Vector autoregression (VAR) is a framework that has been shown to be well suited to predicting for several wind farms simultaneously by considering the spatio-temporal dependencies in their time series. Lasso penalisation yields sparse models and can avoid overfitting the large numbers of coefficients in higher dimensional settings. However, estimation in VAR models usually does not account for changes in the spatio-temporal wind power dynamics that are related to factors such as seasons or wind farm setup changes, for example. This paper tackles this problem by proposing a time-adaptive lasso estimator and an efficient coordinate descent algorithm for updating the VAR model parameters recursively online. The approach shows good abilities to track changes in the multivariate time series dynamics on simulated data. Furthermore, in two case studies it shows clearly better predictive performances than the non-adaptive lasso VAR and univariate autoregression.     

金融机构基层行处如何开展“八小时”以外的员工行为排查

金融机构案件频发的主要因素是不能及时地掌握员工的思想状况,忽视了员工"八小时"以外的生活情趣,导致不能有效采取措施加以防范。本文通过剖析员工行为排查中存在的问题,探讨"八小时"以外行为排查的有效方法,以遏制案件的发生。     

The interchangeability of safety stocks and safety lead time

Due to the uncertainty in estimating both the demand for end products and the supply of components from lower levels, buffering techniques should be included before the loading of a material requirement planning (MRP) system. Safety stocks and safety lead time are two techniques of providing buffering for loading. There have been many studies made concerning the determination of the amount of safety stocks and safety lead time. Some guidelines for choosing between safety stocks and safety lead time for dealing with uncertainty in both demand and supply also have been established. Although these two different methods have been used successfully, it has not been documented that using these two methods in a given situation will yield essentially the same results; that is, the interchangeability of these two buffering techniques has not been explored quantitatively.Since the net influence of safety stocks and safety lead time and their quantitative interchangeability are of major interest, an analytical model is proposed for this study. The lead-time offset procedure for components loading are represented by a matrix model that is based on a lot-for-lot lot-sizing technique. This lead-time offset matrix model is the product of the precedence matrix and the fixed-duration matrix. The precedence matrix is formed according to the total requirement factor matrix and the duration matrix is formed by each component process time. Thus, the lead-time offset matrix will generate the starting period of each component.When the lead-time offset procedure is modeled, the net influence of buffering quantity can be analyzed. The planned safety stock that is normally used to accommodate unexpected demand, shortage in supply, and defects from the operation at each process can be combined with demand to form the master production schedule. The revised lead time due to the integration of the safety stocks can be calculated through the lead-time offset model. The safety lead time may extend the component process time as well as overall production lead time if the designated safety lead time is longer than the available slack time in a fixed lead-time loading system.When the proposed lead-time offset model is further examined, it is found that planned safety stocks at the higher level can buffer the fluctuations of lower level components quantity as well as the fluctuations of same level components quantity. Safety stocks can also buffer shortages that are caused by the delay of raw material and manufacturing processes. Thus, safety stocks can be used to buffer unexpected delay time up to certain limits. A planned safety lead time at higher level component process can buffer the fluctuations of lower level components process time, as well as the same level component process time. The safety lead time can be used to produce additional products to meet unexpected excessive demand up to certain limits under the following conditions: 1. The excessive demand is known before the actual processing of the components in the lowest level. 2. The raw material at the lowest level is available.Although safety stocks and safety lead time are interchangeable in terms of the ability to buffer variations in quantity, the conditions for safety lead time are seldom met in actual practices. Thus, the slack time in a fixed lead-time loading system cannot be considered as an effective measure to substitute safety stocks. However, all or part of the delay in manufacturing processes or the supply from the lower level components can be buffered by the safety stock and the MPS will still be met. From this study, it is obvious that the slack time can be reduced when safety stocks are planned for an MRP system. The reduction of fixed lead-time duration will be beneficial to the overall planning and scheduling in MRP systems.     

Dynamic volatility connectedness between industrial metal markets

Combined with the spillover framework of Diebold and Yilmaz (2009, 2012, 2014) and the TVP-VAR-SV model of Primiceri (2005), this paper studies the dynamic volatility connectedness between six major industrial metal (i.e., aluminum, copper, lead, nickel, tin and zinc) spot and futures markets. The results show that: (1) The total volatility connectedness between industrial metal spot or futures markets has three obvious cyclical change periods with a higher connectedness level; (2) The net connectedness of zinc and copper with other metals has been at a high positive level for a long time, which indicates the two metal markets dominate the industrial metal market; (3) Zinc exhibits the strongest volatility spillovers, while tin exhibits the weakest volatility spillovers, no matter in spot markets or futures markets; (4) The connectedness of realized skewness and kurtosis have similarity with volatility connectedness but the spillover effects of skewness and kurtosis are not as obvious as the volatility spillover effects.     

What drives fluctuations in exchange rate growth in emerging markets – A multi-level dynamic factor approach

Historically, exchange rates in many emerging economies have been volatile. We use a dynamic hierarchical factor model to investigate the driving forces behind these fluctuations in exchange rate growth and find that in recent years, especially since the Great Recession, the common (world) factor has become more important. We also find that, since 2009, US monetary policy and Chinese economic growth have had much greater effects on emerging market exchange rate growth fluctuations. The historical decomposition indicates that 18.8% and 23% of the variations in the world factor after 2009 can be explained by US monetary policy shock and Chinese industrial production shock, respectively.     

Agents, Stakeholders and Corporate Governance in Russian Firms

This paper considers some developments within Russian privatized industrial firms 1992–94 through the lens of Stakeholder-Agency Theory (SAT). Although it has its own shortcomings and weaknesses, SAT, unlike the traditional financial version of Agency Theory, at least contemplates the possibility of a transitional period during which enterprise governance structures can evolve. It is by now widely recognised that in the middle of deep economic crisis, the Russian economy is too volatile for longitudinal studies of formally structured samples of firms over a period of time. In any case, SAT is at a stage of development that has not yet yielded detailed predictions for scientific testing. Yet surveys of recently privatized firms in Russia do provide empirical data away from the origins of SAT, and it is argued that this fresh data suggests new research propositions that can hopefully lead to more theoretical refinement and ultimately testing. At the very least, SAT can be used as a heuristic device, capable of providing a way of looking at complex Russian developments in a structured way. A process of Russian privatization through management–employee buy-outs involving giveaway distributions of shares has secured the compliance of the two main groups of enterprise stakeholders who could have prevented the withdrawal of the State from the governance of industrial enterprises, but has not yet produced a form of corporate governance structure that is likely to survive in the long term without State protection. In the longer term, international competitiveness can only be secured in Russia through investment in new products and processes, and the inadequacies of managers and other employees as sources of investable funds mean that incumbents must generate a more welcoming climate for outside investors. Even after such a short period since privatization and in the middle of a deep economic crisis, some enterprises are already favouring more efficient governance structures in a way consistent with SAT.