The copper and aluminum industries: A review of structural changes

In this article the evolution of the aluminium and copper industries is examined, with a view to deriving policy options open to Third World copper producers, which face a declining rate in the growth of consumption. Market structure, company behaviour and performance are analysed for both industries. The impact of energy and general economic crisis in copper and aluminium industries is assessed and market concentration trends are discussed. We conclude that Third World copper producers must change their basic orientation and become seriously involved in market development.     

Mine capacity and mineral price

The loss of foreign mineral supplies may affect domestic supply and price. To investigate the assumption that prices, a simple mine investment model that relates mine capacity to deposit attributes is used. A test of the model to see how well it approximates industry investment practice illustrates its accuracy. The model suggests that price changes can substantially affect the optimal capacity of planned or existing mines as well as the mineral supply in the USA.     

In situ removal of copper from sediments by a galvanic cell

This study dealt with in situ removal of copper from sediments through an electrokinetic (EK) process driven by a galvanic cell. Iron (Fe) and carbon (C) were placed separately and connected with a conductive wire. Polluted sediments were put between them and water was filled above the sediments. The galvanic cell was thus formed due to the different electrode potentials of Fe and C. The cell could remove the pollutants in the sediments by electromigration and/or electroosmosis. Results showed that a weak voltage less than 1V was formed by the galvanic cell. The voltage decreased with the increase of time. A slight increase of sediment pH from the anode (Fe) to the cathode (C) was observed. The presence of supernatant water inhibited the variation of sediment pH because H(+) and OH(-) could diffuse into the water. The removal of copper was affected by the sediment pH and the distribution of electrolyte in sediment and supernatant water. Lower pH led to higher removal efficiency. More electrolyte in the sediment and/or less electrolyte in the supernatant water favored the removal of copper. The major removal mechanism was proposed on the basis of the desorption of copper from sediment to pore solution and the subsequent electromigration of copper from the anode to the cathode. The diffusion of copper from sediment to supernatant water was negligible.     

Good deposits are not enough: Mining labor productivity analysis in the copper industry in Chile and Peru 1992–2009

Chile and Peru produce almost 45% of world’s mine copper output. This situation reflects their natural endowment and mining tradition, but is also the result of development processes undertaken over the last decades. As a result, both countries multiplied its mine copper production in more than 3 times in the last 20 years. Mining labor productivity played a central role achieving these amazing growth rates. Although there is a consensus about the relevance of this variable for the mining industry, the specific factors behind labor productivity changes are not completely understood.     

The feasibility of decontamination of reduced saline sediments from copper using the electrokinetic process

The remediation of metal contamination in estuarine and reduced sediments is another challenge for the electrokinetic process. Problems result from the complex chemical composition of saline reduced sediments. In the experiments described here copper was added into saline reduced sediments to simulate the natural situation. Two constant voltages were applied across the electrokinetic cell to investigate the effect of an increase in potential difference on the electrokinetic process. Acetic acid at pH 6 and 4 was also added to the cathode in separate experiments to enhance copper removal. The results from this study showed that in the unenhanced experiments most of copper remained in the soil and was unaffected by the electrokinetic process. At the end of unenhanced electrokinetic experiments, the copper concentration was found only to be slightly changed in the anode region. Up to 21% of the copper was found precipitated near the anode when the applied voltage was 10V and this increased to 25% when the applied voltage was 7V. In the enhanced electrokinetic experiments up to 98% of copper was removed from section 1 and precipitated again in sections 2 and 3. This indicates that a significant amount copper removal from the saline sediments may be achieved by the enhanced electrokinetic process.     

USA tackles critical materials

The USA is heavily dependent on foreign sources for supplies of key materials essential to the nation's defence and to the operation of its vital industries. For example, it depends on foreign sources for 22 of the 27 metals considered vital to the country's economy. A public workshop on Conservation and Substitution Technology for Critical Materials was held from 15–17 June 1981 at Vanderbilt University, Nashville, Tennesse, to examine national policies towards resolving the supply problems associated with chromium, cobalt, tantalum and titanium.     

On modelling the global copper mining rates,market supply,copper price and the end of copper reserves

The world supply and turnover of copper was modelled using simple empirical estimates and a COPPER systems dynamics model developed for this study. The model combines mining, trade markets, price mechanisms, population dynamics, use in society and waste as well as recycling, into a whole world system. The degree of sustainability and resource time horizon was estimated using four different methods including (1) burn-off rates, (2) peak discovery early warning, (3) Hubbert's production model, and (4) COPPER, a system dynamics model. The ultimately recoverable reserves (URR) have been estimated using different sources that converge around 2800 million tonne, where about 800 million tonne have already been mined, and 2000 million tonne remain. The different methods independently suggest peak copper mine production in the near future. The model was run for a longer period to cover all systems dynamics and delays. The peak production estimates are in a narrow window in time, from 2031 to 2042, with the best model estimate in 2034, or 21 years from the date of writing. In a longer perspective, taking into account price and recycling, the supply of copper to society is estimated to run out sometime after 2400. The outputs from all models put focus on the importance of copper recycling so that society can become more sustainable with respect to copper supply.     

Optimal stabilization of the copper market: The problem of information

This paper investigates the scope for stabilizing commodity prices by buffer stock interventions. Optimal control is used, rather than simulation, to evaluate the scope for intervention at best. Applications to a world copper market model show that substantial but extensive gains to stabilization are possible. These gains cannot be realised by traditional bandwidth decision rules. An important difficulty is setting the level at which prices should be stabilized. The lack of this information severely reduces the achievable gains.     

World copper market, 1973–1982, and international stabilization policies

This article critically examines international price stabilization policy in relation to the main features of the world copper market and the structural changes that have affected the industry in the decade up to 1982. The first section summarizes the main features of the world copper market, briefly discussing the principal structural changes; the second part examines the recent pattern of investment in copper and changes in ownership of some copper producing companies resulting from the need for improved cash flows due to the adverse effects of the recession; and the third part analyses the practical and theoretical issues relating to the question of price instability. A number of formidable problems are likely to arise from such price stabilization policies and it is concluded that it is because of these difficulties that the policies have not been implemented. Consequently, international commodity agreements designed to minimize or avoid price instability have proved difficult to conclude. New questions on which consensus is likely should be examined to promote intergovernmental co-operation, and hence market stability. With that end in view, this article lists some new questions that could form the basis of an agenda for exploratory intergovernmental discussions on copper.     

Resistance of pulmonate snail populations to repeated treatments of copper sulfate

Two species of pulmonate snails,Lymnaea cat-ascopium andPhysa integra, were collected from Douglas and Houghton Lakes. Snail populations from the former lake (pristine) had never been exposed to copper sulfate, whereas those from the latter one (treated) had been subjected to the molluscicide for more than 40 years. Molluscs from the treated lake were more resistant to the copper at concentrations of 0.5 and 1.0 ppm than those from the pristine lake. Furthermore, larger lymnaeids had a higher survival rate than smaller ones.     

Modelling future copper ore grade decline based on a detailed assessment of copper resources and mining

The concept of “peak oil” has been explored and debated extensively within the literature. However there has been comparatively little research examining the concept of “peak minerals”, particularly in-depth analyses for individual metals. This paper presents scenarios for mined copper production based upon a detailed assessment of global copper resources and historic mine production. Scenarios for production from major copper deposit types and from individual countries or regions were developed using the Geologic Resources Supply-Demand Model (GeRS-DeMo). These scenarios were extended using cumulative grade-tonnage data, derived from our resource database, to produce estimates of potential rates of copper ore grade decline.The scenarios indicate that there are sufficient identified copper resources to grow mined copper production for at least the next twenty years. The future rate of ore grade decline may be less than has historically been the case, as mined grades are approaching the average resource grade and there is still significant copper endowment in high grade ore bodies. Despite increasing demand for copper as the developing world experiences economic growth, the economic and environmental impacts associated with increased production rates and declining ore grades (particularly those relating to energy consumption, water consumption and greenhouse gas emissions) will present barriers to the continued expansion of the industry. For these reasons peak mined copper production may well be realised during this century.     

Leaching characteristics of copper flotation waste before and after vitrification

Copper flotation waste from copper production using a pyrometallurgical process contains toxic metals such as Cu, Zn, Co and Pb. Because of the presence of trace amounts of these highly toxic metals, copper flotation waste contributes to environmental pollution. In this study, the leaching characteristics of copper flotation waste from the Black Sea Copper Works in Samsun, Turkey have been investigated before and after vitrification. Samples obtained from the factory were subjected to toxicity tests such as the extraction procedure toxicity test (EP Tox), the toxicity characteristic leaching procedure (TCLP) and the "method A" extraction procedure of the American Society of Testing and Materials. The leaching tests showed that the content of some elements in the waste before vitrification exceed the regulatory limits and cannot be disposed of in the present form. Therefore, a stabilization or inertization treatment is necessary prior to disposal. Vitrification was found to stabilize heavy metals in the copper flotation waste successfully and leaching of these metals was largely reduced. Therefore, vitrification can be an acceptable method for disposal of copper flotation waste.     

Incorporating environmental issues into optimum cut-off grades modeling at porphyry copper deposits

Cut-off grade is defined as the grade which discriminates between ore and waste within a given orebody. Determination of a complete optimum cut-off grade policy is a very important function during mine life. Using the modified optimum cut-off grade model presented in this paper not only the net present value of a porphyry copper mining project is maximized, but also the adverse environmental impacts of the project are minimized simultaneously. This methodology is more effective in long-range planning. For showing the effectiveness of the model, two scenarios are considered in a hypothetical deposit and the results show that incorporating the modified optimum cut-off grade policy, the net present value will be increased by 3.6% in comparison with the Base Case.     

Quantification and spatial characterization of in-use copper stocks in Shanghai

Shanghai is the largest industrial and commercial city of China, where in-use stocks of metals are likely to be significant. The in-use stocks of copper in this city are thus established by an extensive “bottom-up” study. Spatial distribution of copper stocks within Shanghai has further been characterized for better understanding of copper utilization pattern of this city. For the year 2012, the results are a total stock of 914.6 Gg Cu, and 38.4–64.1 kg Cu per capita. Nearly 94% of copper stocks distribute in subcategories of electric power transmission and distribution, water transmission and distribution, buildings, and household durable. Features of spatial distribution show that three central districts of Jing An, Hong Kou and Huang Pu have the spatial density of more than 1 Gg/km². And Chong Ming county and Jin Shan District have the lowest spatial density of about 0.01 Gg/km². It has been found that the copper stock density within Shanghai is largely determined by population density and economic development level.     

Optimization of the continuous biosorption of copper with sugar-beet pectin gels

Sugar-beet pectin xerogels obtained from residues of the sugar industry are an adequate material for metal recovery from effluents in continuous systems. The xerogels were used as a biosorbent for copper removal in a fixed-bed column. The performance of the system was evaluated in different experimental conditions: flow rate, bed height, inlet metal concentration and feeding system (drop and reverse). The effect on the biosorption parameters (saturation time, amount of adsorbed and treated metal, column performance and metal uptake) and the shape of the breakthrough curves was determined. The saturation time increased with increasing bed height but decreased with increasing feed flow rate and inlet metal concentration. Preferential flow channels greatly influenced the metal uptake and column performance. Copper was completely desorbed with 0.1 M HNO₃. Additionally, the column data fitted both the linear and nonlinear expressions of the Thomas model.     

Characteristics of a bioxalate chelating extraction process for removal of chromium,copper and arsenic from treated wood

The disposal of wood waste treated with chromated copper arsenate (CCA) is a problem in many countries. We have proposed a novel chelating extraction technique for CCA-treated wood using bioxalate, a solution of oxalic acid containing sufficient sodium hydroxide to adjust the pH to 3.2, which is an effective way to obtain an extraction efficiency of 90% for chromium, copper, and arsenic. The purpose of the present study was to investigate the characteristics of bioxalate extraction of CCA-treated wood. Extractions of CCA-treated western hemlock chips with solutions of bioxalate, oxalic acid, and sodium hydroxide were carried out. The use of bioxalate was confirmed as the most effective extraction technique for chromium, copper and arsenic, with an efficiency of 90%. Extraction with simple oxalic acid was ineffective for copper (less than 40% extraction efficiency), but effective for chromium and arsenic, with 90% efficiency. Sodium hydroxide showed a similar tendency, being ineffective for chromium and copper (less than 20% extraction efficiency), but relatively effective for arsenic (around 70–80% efficiency). We also discovered an interesting phenomenon whereby the addition of sodium hydroxide to a simple oxalic acid solution during the oxalic acid extraction progress resulted in dramatically increased extraction efficiency for copper, chromium and arsenic, up to 90%. Although oxalic acid was ineffective for copper extraction, the addition of sodium hydroxide during the oxalic acid extraction process rendered it effective.     

Copper recycling and scrap availability

According to existing estimates, available old copper scrap has more than tripled over the past 40 years. Secondary production (that is, copper produced from recycling old scrap), however, has only doubled. Indeed, over the past 10 years, while copper consumption and primary production have continued to expand briskly, while available old scrap has increased by over 35%, secondary production has actually stagnated.For a world concerned with sustainable development and the quality of the earth's environment, this performance is disappointing and in need of explanation. Other things being equal, one would expect the amount of recycling to increase with the availability of scrap, as many econometric models of the world copper market developed over the past several decades explicitly assume.The key to understanding sluggish growth in secondary production, this paper argues, is distinguishing carefully between (1) the flow of old scrap that arrives each year from products reaching the end of their useful lives during the year and (2) the available stock of old scrap that was not recycled during earlier years presumably because it was too costly to do so. Using an econometric model, the paper shows that old scrap stocks, which have contributed most of the increase in available old copper scrap over the years, have a very modest impact on secondary production. Old scrap flows have a much greater effect, but they account for only about 4% of the available old scrap for any given year.     

The composition and environmental hazard of copper slags in the context of the Basel Convention

A recent comprehensive review of the characteristics and utilization of copper slags encourages (properly) several applications for this important pyrometallurgical byproduct. However, the review does not include possible environmental effects from these slags. The United Nations Basel Convention on the Transboundary Movement of Hazardous Wastes and Their Disposal characterizes copper compounds that exhibit specified hazard characteristics as hazardous wastes. In 1996, the Convention considered further characterization of these and other compounds and substances. The final characterization of copper slags is as non-hazardous, i.e., exempt from control. This decision was based in part (if not largely) on the data that are presented here. Literature reports were used to accumulate data describing the chemical composition and acid leaching of commercial copper slags from three countries. From these data, average values of chemical composition and their statistical confidence limits (95%) were calculated. The variability of the chemical analyses of three commercial slags produced over 19 or 20 months were statistically analyzed and shown to be small. The concentrations of toxic heavy metals in the slags are low and the frequency distributions of the values are narrow. Most of the data are normally distributed, validating the use of the statistics used and permitting predictions of likely values. The amounts of heavy metals extracted by an aggressive standard acid leach procedure are low and well below the United States. regulatory levels derived from drinking water standards. The results for total composition and leaching illustrate why the U.S. Environmental Protection Agency made a regulatory determination that such slags are not hazardous wastes. Later, in 1996, the Basel Convention Technical Working Group concurred and the Parties to the Convention adopted their recommendation.     

Reclamation of wastes contaminated by copper,lead, and zinc

Waste materials containing toxic levels of copper, lead, and zinc, such as mine and smelter wastes, present difficult conditions for the establishment of vegetation. This article reviews the many attempts which have been made to reclaim these wastes. Inert wastes from mining and quarrying operations, such as slate quarry waste and certain colliery shales, seem to be good materials for reclaiming wastes contaminated by copper, lead, and zinc. Organic wastes, such as sewage sludge and domestic refuse, may provide only a temporary visual improvement and stabilization of the toxic materials.Nontolerant plant materials may often be planted directly on modern waste materials, which are less toxic than they were in the past. However, tolerant plant materials are needed for revegetating waste materials produced by early and more primitive extraction methods.     

资源化治理糖厂"三废"

充分利用蔗糖厂的条件,采取"以废治废"和资源化系列技术治理蔗糖厂"三废",引入清洁生产概念,将污染物治理的产物全部转化为可就地使用的农肥,形成蔗糖业的良性循环,有效促进了蔗糖业的可持续发展.