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By G. A. Kordosky

The concept of selectively extracting copper from a low-grade dump leach solution followed by stripping the copper into an acid solution from which electrowon copper cathodes could be produced occurred to the Minerals Group of General Mills in the early 1960s.This simple, elegant idea has resulted in a technology by which about 2.2 million tonnes of high quality copper cathode was produced in year 2000. The growth of this technology is traced overtime with a discussion of the key plants, the key people and the important advances in leaching, plant design, reagents and electrowinning that have contributed to the growth of this technology. Some thoughts on potential further advances in the technology are also given.

Jan 1, 2002

The observation of lower-than-predicted Fe/Cu ratios in the cementation of copper on iron in tests at elevated temperatures indicated that some other reaction was contributing to the reduction of cupric sulphate in addition to the reduction by elemental iron. Experiments showed that the copper sponge, which initially formed on the iron, subsequently reduced the cupric sulphate giving the products cuprous oxide and sulphuric acid.Tests were undertaken to determine the rate and equilibrium conditions of the reduction reaction with variations in the types of the reducing agent and solution parameters. The reaction first became apparent at temperatures above 50°C and as it ceased at pH 1·8 it was possible to induce further reaction by alkali addition.

Jan 1, 1974

Within CRLÆs lifetime there have been a number of products that have proceeded through their life cycles. In each case market forces and technological advances have forced the cessation of the product. The company has then had to develop alternative outlets for its copper. Sometimes it has produced a similar product to fill the same market. In other cases the extra copper is sold as cathode. Today, CRL produces no semi-fabricated copper products and all cathode is sold. More recently, CRL has ventured into the sale of technology and manufacture of cathode motherplates. This area, whilst it is not what had been a traditional area of core business, has been found to be profitable.

Jan 1, 1998

By L. G. Evans, C. Rampacek, G. A. Freeman

A large aggregate tonnage of oxidized and mixed oxide-sulfide copper ore of the southwestern U.S. is not amenable to conventional flotation concentration or sulfuric acid leach treatment. Most of the ores contain chrysocolla as the principal oxide copper mineral, for which no successful commercial flotation method has yet been developed. Acid leaching some ores is not feasible since they contain substantial quantities of calcite and other acid-consuming constituents. Other ores decrepitate during leaching or contain excessive slime and clay minerals which cause plugging of the ore beds.

Jan 10, 1961

By Parker A. J, Grimsey E. J

Studies have been carried out on the dead roasting of a copper-iron and a copper-nickel-iron sulfide concentrate, followed by segregation roasting with coal and leaching with either curpric sulfate in aqueous acetonitrile or cupric chloride in brine solution to preferentially solubilize copper. The effect of dead roasting and segregation roasting conditions on the overall leaching of copper and the separation of copper from iron and iron and nickel is reported. An excellent separation of copper from iron and a good separation of copper from iron and nickel can be obtained provided sulfur is removed to 0.5 per cent or less during the dead roast and provided the coal addition and temperature of the segregation roast are near the minima required for the segregation of copper.

Jan 1, 1983

In eastern China, most of the copper skarn deposits occur in folded troughs which are controlled by the EW-trending faulted fold systems (the Pal-Asian geotectonic domain), and the NNE-trending rift or fault zones (the Marginal-Pacific geotectonic domain), particularly the later. From the north to the south, there are four troughs hosting the main copper skarn deposits in eastern China: the Yanliao Trough, the Yangzi River Trough, The Qiantang-Yuanshui Trough and the Zichen Trough. There are more than 30 copper skarn deposits in eastern China, and ore reserves of each deposit are between 30 to 100 Mt with average grades over 1% Cu.    Most of the large copper skarn deposit-related intrusions are Mesozoic in age (170 to 100 Ma) and were emplaced during the Yanshanian Movement. Outwards from the intrusion bodies, both the skarn alteration and mineralisation show certain patterns of zonation. Mineral assemblages indicate a relatively high oxidisation state during metasomatic alteration and mineralisation. Sulphur isotopic work indicates that most d34S values of the sulphides are between ~4 to 3ë suggesting a common magmatic sulphur source. Fluid inclusion and oxygen isotopic studies suggest that early-stage fluid shows magma-related fluid characteristics although meteoric water was involved during late-stage alteration.

Jan 1, 1995

By Drew GJ

Smelting is a process in which heat is applied to ores to produce metals. Impurities are removed by segregation in the slag, or converted to gases or sublimates and discharged up the flues. Mate- rials delivered into the smelter have generally been previously concentrated or processed at the mine, and the size of their particles, and also their chem- ical composition, greatly affect the smelting proc- ess. Some impurities are more difficult to remove than others, and are more objectionable in the finished product. The first metal mine in Australia was opened near Glen Osmond in South Australia in 1841, for silver-lead ore. It was followed by the Kapunda Mine for copper in 1844 and by the very signifi- cant Burra Mine, also for copper, in 1845 (Figure 1). A major part of their ores could not be exported profitably for smelting in England and Wales where the large smelters were then located. In addition to treating ores from Cornwall these also smelted ores from recently opened mines in Cuba, Chile, and Mexico. The Welsh smelting process (Figure 2) was developed over a period of years to utilise Welsh coal to treat copper ores particularly from Corn- wall. The first step consisted of a calcination to remove sufficient sulphur from sulphide ores so that subsequent melting operations would produce copper matte, a copper-iron-sulphide which melted at about 1050¦C. Subsequently refined to white metal with the addition of carbonate and oxide ores when these were available, and often through an intermediate step of blue metal, this matte was finally oxidised to pure copper, or as pure as it could be made in those days. The movement of metal towards greater purity was matched by a reverse flow of slag, carrying reducing quantities of copper, so that the slag rejected from the first melting process carried the minimum quantity of copper. Chemical analysis was virtually unknown. Materials were assayed in the laboratory by a small scale smelting process, and the purity of the final refined copper was judged b} the ease with Mhich it could be hammered into thin sheets.

Jan 1, 1987

By Nickolas J. Themelis

The role of copper in the economy will not diminish in the 21st century. Following the tenets of industrial ecology, production and use of copper must take into account both human needs and also how to minimize "collateral" effects on the environment. Dispersive uses will be phased out and post-use recovery of copper will increase. This will result into an advantage for smelting processes that can accommodate mixed metal scrap and waste streams. The bath smelting processes of Noranda and Mitsubishi will continue to make progress but the dominance of the Outokumpu flash smelting will not be challenged until the Noranda reactor overcomes the obstacles to the direct production of copper, thus eliminating the need for a converter.

Jan 1, 1999

By Kathryn C. Sole, Owen Tinkler

"Although the first large-scale application of copper recovery by solvent extraction (SX) took place in Zambia in the early 1970s, it is only in the last decade that this technology has become widely employed in this part of the world and is now a mainstay unit operation in most copper hydrometallurgical flowsheets. The mineralogy of the ores in the African Copper Belt, and hence the characteristics of the African leach liquors, differ significantly from those in Chile and the south-western USA, where copper SX has had a long and successful history. These differences provide operators, metallurgists, reagent vendors and engineers with many challenges: new approaches are needed to adapt this technology for successful implementation in this region. This paper examines typical operating practice in the African Copper Belt, discusses differences compared with other parts of the world and looks at some of the challenges and opportunities presented by these flowsheets. INTRODUCTION Following the success of the Rancher’s Bluebird and Bagdad solvent extraction and electrowinning (SX–EW) operations in Arizona in the late 1960s, the Tailings Leach Plant at Chingola, Zambia became the first large-scale copper SX plant in the world, commissioned in 1974. Despite the equipment design now being outdated, this plant still continues to operate successfully, indicating the versatility and adaptability of this technology. Today, there are some 75 copper SX operations worldwide with cathode production above 10 kt/a. The top ten producers currently account for some 40% of the global 4.3 Mt/a SX–EW copper production. South America (predominantly Chile and Peru) is the largest copper cathode-producing region, with annual production of some 2 Mt. The Central African Copper Belt (Zambia and the Democratic Republic of Congo (DRC)) is second, with cathode production of 1.2 Mt/a and North America (USA and Mexico) third, producing close to 0.8 Mt/a Cu (Cytec data, 2014). The remaining 0.35 Mt/a comes from all other regions combined (referred to as “Rest-of-World”). Current and future operations in Zambia and the DRC are summarised in Figure 1. The industry in this region is characterised by a large number of small (3 to 20 kt/a) plants, mainly Chinese-owned, and a few very large (>200 kt/a) operations, owned by major multinational corporations. This paper examines typical operating practice in the African Copper Belt, discusses the differences compared with other parts of the world and looks at some of the challenges presented by the conditions, as well as innovations in flowsheets, reagents and operating conditions that have been introduced in these circuits."

Jan 1, 2015

Copper waste dump leaching is growing in importance because of the.large tonnages (up to 250,000 ton/day) of low grade waste rock available from open cut mining of copper deposits and proof that controlled leaching of copper from such dumps can be profitable.Overburden or waste rock, ranging in size from large boulders to fines, is dumped as cheaply as possible on sloping sites. Copper is leached from the dumps by applying up to 12,000 gal/min of leach solution (a combination of spent solution from cementation and make-up water) to the top of the dumps by various techniques.Efliuent from the dumps is sent to a cementation plant for copper recovery.Factors which may be controlled, either directly or indirectly, to give a controlled copper content in the dump efliuent (usually 1-2 g/l.) are the cycle of operations (i.e. the alternate wetting and drying periods), thevolume of solution applied to the dump, pH, Fe2+ and Fe3+ content or redox potential, oxygen content, bacteria and their necessary nutrients, and temperature.Dissolution of oxide copper minerals appears to be mainly a function of acid concentration. Copper sulphide minerals need oxidation for dissolution to occur and this is accomplished by a combination of oxygen,ferric ion, and bacteria. Oxidation of pyrite, oxidation of Fe2+ to Fe3 +, and hydrolysis of Fe3+ are of some importance in leaching practice. The presence of gangue carbonate minerals is detrimental.Physical factors connected with penetration of solution into large rocks are important and the treatment of an individual dump usually extends over a period of many years. Recovery of copper from solution is usually achieved by cementation with iron (usually in the form of crumpled cans) but the use of sponge iron is becoming more important. Iron consumption varies from 1 to 4 lbiron per pound of copper. Preconcentration of the copper in the efliuent solution by solvent extraction followed by electrolysis may become a useful method.Application of dump leaching techniques to metals other than copper depends on finding an economic method of recovering the metal from solution...

Jan 1, 1967

Rajor intrusion-related Cu and Au dep- osits along the Cordilleran-type central Andean margin and in the western Pacific island arcs constitute a series of discrete, linear belts which correspond to limited (414 m.y.) metall- ogenic epochs. The most important metallogenic belts, all of Cenozoic age, are inferred to have been generated during relatively shallow subduction of oceanic lithosphere beneath con- vergent margins. Geological and isotopic evid- ence suggests that magmatic rocks and associated Cu and Au mineralization were derived from asthenospheric mantle sources, which were enriched in a variety of elements (metals, alkalis, S) by dehydration of subducting oceanic crust. Where exceptionally rapid, low-angle 3ubduction took place beneath very thick (>50 km) continental crust, as in the central Andean Altiplano in the Miocene and southwestern North America during the Laramide, ore-related magmas underwent wholesale crustal contamination. However, the associated Cu-Au mineralization is the same as that developed in primitive island- arc crust. In particular, the by-product Au and So contents of porphyry Cu deposits are inde- pendent of crustal thickness and the degree of crustal contamination as determined isotopic- Ally.

Jan 1, 1987

By A. Block-Bolten

Copper concentrates from northern Peru contain large amounts of arsenic and antimony in the form of sulfosalts like enargite, tennantite and tetrahedrite. These impurities affect up to 30% of Peruvian copper production. Under the sponsorship of the Instituto Geologico Minero y Metalurgico in Lima a project to separate copper from arsenic without pollution of the environment is being carried out at the National University of Trujillo in Peru. The U.N.T. process is unique in the respect of using .low melting salts as solvents, and sulfides of metals with high cation potential as destructors of the complex sulfosalt molecules. Laboratory scale experiments have given encouraging results but interesting and difficult problems developed on scale-up. The process is pyro-hydrometal-lurgical and under certain circumstances its economics are promising.

Jan 1, 1981

By Dachun Liu, Baoqiang Xu, Bin Yang, Yong Deng, Heng Xiong, Xiumin Chen

"In this paper, vacuum distillation technology has been employed to study the possibility and regularity of separating copper and enriching lead, silver and other valuable metals from copper- based multi component alloys. The result of experiment indicated the practicability of vacuum distillation dealing with copper base complex multi-component alloy to separating lead and silver, when the vacuum distillation temperature was 1637K, distillation time was 60min; residual gas pressure was 20-30Pa, the removal rate of silver was 95.86%, of lead was 99.63%; the evaporation rate of copper was 0.745%. The removal rate of arsenic, antimony and tin respectively were 83.09%, 48.12% and 24.54%. Vacuum distillation method is applicable for dealing with the copper-based multi component alloys, silver and lead can realize effective recovery.IntroductionCopper generally go with lead mineral, therefore, to remove copper from lead becomes an inevitable link in lead smelting. Dross from removed copper usually contains lead, arsenic, antimony, tin and noble metal silver. In abroad, soda ash-iron dust is adopted to process copper dross of this kind. The outcomes of this process are lead matte, wet lead, scoria smoke dust etc[1~5] The dominant components of all the outcomes are copper and lead. Moreover, in the process of tin smelting, copper contained by-products are produced, such as, crude tin alloy, tin lead electrolytic anode slime and so on. Copper content of all the products are ranging from few percentages to several tens percentage. Those products, no matter merge into main producing process, or separate treatment cost losses of valuable metal. For one hand, the containing of copper of outcomes from pyrogenic attack is less than 50%, for the other hand, a lot of valuable metal need to be processed, which increase the cost of retrieve."

Jan 1, 2013

By Zay Jeffries

AN acute current shortage of copper, with the prospect that conditions may become worse, indicated by Office of Production Management information. Present estimates of copper requirement for defense indicate that nearly all the available metal will be required in the future for this purpose. Severe dislocations are, expected, but the objective is to distribute the copper available for civilian use in such a manner as to minimize these dislocations. The advisory committee on metals and minerals has been asked for a suggestions which may be helpful in meeting this situation.\

Jan 1, 1941

By James A. Lewis

It is the purpose of this paper to show the importance of sand characteristics, when combined with other physical data, in evaluating production obtained by secondary recovery operations, and to indicate the benefits to be gained from the application of these principles to primary production.

Jan 1, 1942

By S. H. Ash

THE information obtained by examining and analyzing the core drillings from 15 diamond-drill holes shows that with the proper equipment little difficulty should be experienced while sinking the shafts at the 15 selected sites. Although a number of holes penetrated formations containing a high percentage of silica,, the health hazard from dust can be removed by using proper dust-control equipment. Methane was detected in small amounts in only one (hole 5) of the boreholes. The methane hazard should present no difficulty if adequate ventilation is employed while sinking the shafts.

Jan 1, 1952

By Lees M. G, Vitnell B. W

The post-war need to increase coal production promoted an intensive drilling campaign. Ineffectiveness in core recovery inclined the coal industry towards percussion drilling rather than diamond drilling. The Joint Coal Board, recognising the greater potential of core drilling, has actively encouraged improvement in techniques and equipment. One outstanding need was a barrel which, over and above other improvements being achieved, would permit recovered core to be examined before it had been subjected to the increased fragmentation and displacement which to date has been inevitable except in core which has been drilled in solid sticks û as New South Wales coal rarely can be drilled. In conjunction with Triefus Pty Ltd a barrel with a split inner tube has now been evolved, as a result of which, core can be more accurately logged, division in to lengths for analysis more aptly made, any core loss more reasonably allocated to appropriate plies, and a greater percentage of core recovered û of the order 95 per cent and more. The one half of the split inner tube is lifted from the other and the logging completed before the core is disturbed.

Jan 1, 1957

Recent developments in diamond drilling practice have been chiefly 'concerned with modifications in drill design and 'operating technique whereby an increase in daily footage rates and reduced footage costs have been achieved without any marked improvements in the recovery of core. This trend is perhaps due to the general acceptance by the mining and drilling engineer alike of the belief that diamond drilling has definite limitations in exploratory work on mineral deposits characterized by irregularities in continuity and grade, such a belief arising from the fact that drilling technique has not yet evolved coring devices to ensure the full recovery of the rock and mineral formations penetrated.Current diamond drilling operations at Moonta and Wallaroo Mines, carried out by the South Australian Department of Mines, have attained remarkable results in completely eliminating core-loss by the use of a special double-tube core barreI.It is considered that assays of borehole samples taken with this special barrel have a reliability comparable, if not superior to that of similarly situated mine samples and, provided they are spaced satisfactorily, can be used as, a basis for calculating tonnage and grade. Formerly, with only partial core-recoveries, positive borehole results on narrow irregular lodes, such as those in the Moonta and Wallaroo Mines, could be accepted mainly as indications of the presence of mineralization, and could have only a limited bearing on estimates of ore reserves.The value of this special double-tube core-barrel lies In the fact that it guarantees good core recovery and, therefore, good samples, and eliminates the need for sludge-sampling, which is prone to give unreliable assay results from several causes, such as gravity concentration in the bottom of the hole and return water losses which cannot be overcome.In view of the increasing demand for minerals and the probability that the search for them will be carried on largely by boring, it is felt that it would be of interest and value to direct the attention of mining engineers to core-recovery results obtained by diamond drilling plants in South Australia and the features of the special core-barrel, designed by the writer, which has made this possible. Also, the writer is desirous of placing on record two other core-recovery devices designed to extract accurate samples in relatively soft or unconsolidated formations. The latter are used with percussion and calyx plants, respectively and their value has been proven on phosphate rock and coal deposits in South Australia.

Jan 1, 1943

By N. Simpson

Low carbon 11.5% chromium stainless steels are finding increasing use in industry as square or rectangular tubing material for the construction of structures by welding. During processing, resistively welded circular pipes are bent into square or rectangular shapes. During this process longitudinal cracks can sometimes develop atone of the inner corners of the section. An investigation has shown that the processing of round into square tubing with very sharp corners can cause excessive cold working at the inner corners of the squared tube. This, together with the high tensile residual stresses and a susceptible microstructure due to the presence of grain boundary carbides, can result in brittle cleavage cracking. Measures that can be used to reduce the problem are described.

Jan 1, 2003

South Australia was founded as late as 1836, forty- eight years after New South Wales, yet within five years had announced the first discovery of metals in Australia. Throughout the 1840s the mining of silver-lead, then copper, spread north through the Mount Lofty and Flinders Ranges creating a thriving industry, years before the discovery of gold in the eastern colonies in 1851. The first significant mine was Kapunda (1842), followed by the much bigger Burra (1845) and other copper finds at Tungkillo, Worthing, Cal- lington, and North Rhine.

Jan 1, 1987