Search Documents

By J. J. Laffin

In the pursuit of comfort and safety, the wonders of science have given us controlled heating and cooling, thus enabling us to enjoy all the aspects of present-day living to an extreme never previously •envisaged. Man's attempt to conquer the elements largely involves con-trolling the temperature around him. Without having conquered this aspect, his body energy would be consumed in trying to maintain physical comfort, rather than being invested in the explorations which have resulted in man's control over the forces of nature. The indirect methods used to obtain the most agreeable temperature environment were developed because of the natural tendency to strive for increased safety, convenience and comfort. Until the twentieth century, when heat generated by atomic fission became a reality, man's only source of heat, except for that of the sun, came from his discovery of fire.

Jan 1, 1962

By Sanaz Mosadeghsedghi

The feasibility of the application of electrodialysis in separation of light and heavy rare earth elements (REE) in synthetic solutions was investigated. The experiments were carried out using single and binary solutions of a light (cerium) and heavy (ytterbium) REE. The effects of electrical voltage, electrical current, and the addition of complexing agent (EDTA) to increase the separation selectivity were investigated. Separation of Ce and Yb was achieved in binary solutions with and without the addition of EDTA. Higher degrees of separation were seen at higher voltages. Ce–Yb separation was more significant in the presence of EDTA. The separation factor of Ce–Yb and Ce–Yb-EDTA were 1.44 and 2.60, respectively.

By Shailin Lalloo, Allan B. Nesbitt

A fluidised bed was exposed to high gravities by placing it in a centrifuge. The bed expansions were measured and compared with the bed expansions predicted by the Richardson-Zaki model (1954). The Richardson-Zaki model was found to predict effectively the fluidisation behaviour of defined particles in this increased gravity environment.

Jan 1, 2003

By J. Philip Neal

Feldspar is no example of special mineralization in isolated spots: it can usually be found within a mile or so of almost anywhere. Along with silica sand, it is a major part of our world's total mineral composition. This fact imparts to it an economic status different from a sulfide ore, or potash, or phosphate. While every feldspathic "stringer" does not possess economic potential, the generous distribution does yield a high statistical frequency of good feldspar ore bodies: the adjective "good" being subject to some flexibility of interpretation. The strong chemical bonds of this alkali aluminum silicate give it certain use advantages, but under present technology its individual elements cannot practically be separated to create aluminum, potassium, sodium, silicon - or their oxides. Its present uses rely upon chemical inertness - as in fillers; and on its physical melting characteristics and their effect in glass, enamel, or ceramics.

Jan 1, 1973

By Bodnaras G. E, Sceresini P. A

The Filblast Cyanidation Process incorporates the advantages of intense high shear mixing, high dissolved oxygen concentration and high pressure to achieve extremely rapid gold dissolution rates. This is made possible by the unique design of the Filblast gas shear reactor. The reactor is a rugged and compact in-line device. The outer casing is protected by a polyurethane coating and the internal parts are of wear resistant polymer. The largest unit built to-date has overall dimensions of 1200 mm length by 300 mm diameter and has a capacity of 150 dry tonnes per hour at 40 - 45 per cent solids. Service life at this throughput is at least three months. The process may further be applied to high temperature leaching of refractory gold ores or other metals. Wear resistant metal or ceramic materials would be employed for this duty. Four mines are currently employing the Filblast Process for treating a variety of ore types ranging from highly reactive, almost impossible to treat, pyrrhotite/arsenopyrite to deeply weathered clay ore which forms a highly viscous pulp. The effect of shear thinning has resulted in improved adsorption kinetics resulting in higher carbon loading and reduced soluble gold loss. Total tonnage treated is approximately four million. Operating costs which include leasing and maintenance charges for the Filblast and pump power costs are about 16 cents per tonne. This is equivalent to about ten per cent of savings. Laboratory scale units having capacities up to 30 litres/min are available for test work but laboratory testing techniques so far developed do not accurately reflect the oxygen and cyanide savings which have been achieved in the plant.

Jan 1, 1994

By B. J. S. Sceresini

The Filblast Cyanidation Process incorporates the advantages of intense high shear mixing, high dissolved oxygen concentra­tion and high pressure to achieve extremely rapid gold dissolu­tion rates. This is made possible without suffering from high energy or wear rates by the unique design of the Filblast gas shear reactor. The reactor is a rugged and compact in-line device which can be constructed from a variety of wear and chemical resistant materials. High temperature tolerance is also possible so that the device can be incorporated into a pressure leach circuit with significant capital cost savings because of the high capacity to volume ratio that is an inherent feature of the device. For cyanidation applications the outer casing is protected by a polyurethane coating and the internal parts are of wear resistant polymer. The largest unit built to date has overall dimensions of 1200 mm length by 300 mm diameter and has a capacity of about 150 dry tonnes per hour at 40-45 % solids. Service life at this throughput is at least three months. Six mines are currently employing the Filblast Process and another six are conducting plant trials. The ore types range from highly reactive, almost impossible to treat, pyrrhotite/ arsenopy­rite to deeply weathered clay ore which forms a highly viscous pulp. It has been found that the effect of shear thinning has resulted in improved leaching and adsorption kinetics resulting in higher carbon loading and reduced soluble gold loss. Total tonnage treated is approximately eight million tonnes per annum. This paper presents the operating benefits and cost savings which have been achieved in four plants, two treating oxide/ sulphide ore blends and two treating highly reactive sulphide ore and concentrate. Filblast leasing and maintenance charges and pump operating costs are about ten percent of the benefits. A conceptual cyanidation circuit based on the Filblast Cyanidation Process is also discussed. The Filblast System is an in-line pressure leach aerator/ reactor which generates very high shear and greatly enhances mass transfer rate by generating extremely small gas particles where oxygen gas is required for oxidation reactions and/or utilising the high shear characteristics to minimise the diffusion boundary layer. Both of these rate limiting factors effect the rate mechanism for gold cyanidation. Initially two multi-stage Filblast aerator cartridges formed a leach train but now the trend is to install a single submersible cartridge of equivalent perfor­mance. This design simplifies installation and minimises change-out times. However the in-line concept can be employed where high pressure leaching or pressure oxidation is required. The reactor is submerged in the leach tank so that the mass of gas micro-bubbles contained in the discharging slurry is entrained in the agitator vortex and is thoroughly dispersed throughout the tank. A diagrammatic representation of a leaching circuit incorpo­rating the Filblast Reactor is shown in Figure 1. The recirculation pump takes new feed directly from the cyclone overflow trash screen either under gravity or pump fed and recirculates the balance to maintain 250 - 270 m3/h total slurry flow. All of the leach feed slurry gets at least one pass through the Filblast thereby eliminating short-circuiting. Typically a 6/4 EAH Warman pump drawing 60-70 kW is required to circulate 250 m3/h through the system. The back pressure generated by the Filblast is in the range of 400-500 kPa depending upon pumping rate, pulp density and slurry rheology. The high shearing rate effectively negates the viscous effect of slurries and the addition of a gas further reduces the pulp density by virtue of the intensely aerated, homogeneous medium. The gold leaching Filblast cartridge elements are made of polyurethane but stainless steel, ni-hard, rubber or ceramics can be used depending on the operating temperature and design duty. The efficiency of the Filblast Leach Reactor in gold cyani­dation is due to the extremely efficient mixing, oxygen dissolu­tion and surface polishing action of the Filblast design. Either air or oxygen may be used but Atomaer recommend the use of oxygen because of the rate benefits gained from cyaniding at [02] significantly > 20 ppm D O in the reactor. Very high DO concentrations have been measured; in excess of 50 ppm. There is some debate as to whether the value is a true measure of the DO or the oxygen meter sensor is measuring the effect of a mass of very fine bubbles of free oxygen. Regardless of the fact the reactor has registered some amazing gold dissolution rates commonly in excess of 80 % during transit of the pulp through the reactor. The elapsed time is less than half a second!

Jan 1, 1995

By James A. Finch, Robert E. McIvor

"This paper presents the development of a new grinding circuit steady-state modeling system. It is fundamentally based on the “functional performance equation”, which has now been used to improve the performance of numerous grinding circuits. This equation characterizes the two distinct efficiencies that are at work in a ball milling circuit, and how these relate to overall circuit productivity. It does so based on the particle size chosen to distinguish between coarse and fine (product size) material. Now, by applying it to all the material size classes, a simple yet reliable ball mill model was created. Combined with cyclone recoveries, the complete, detailed grinding circuit performance can be exactly reproduced mathematically by the computer program. It can then be used with separate process equipment application engineering methods to systematically engineer grinding circuit improvements. The development, features, uses and limitations of the system are described.INITIAL DEVELOPMENT OF THE CIRCUIT MODELThe Functional Performance Equation for Closed Circuit Ball (or Pebble) MillingIt has been shown that closed grinding circuit performance can be effectively characterized by the “functional performance equation” for closed ball or pebble milling circuits (McIvor, 2006a). One method of its derivation is summarized here for convenient reference.First select a cut-off size to define “coarse” versus “fine” or product size material for the grinding circuit. Any particle mesh size can be used to differentiate between coarse material and fines, but the circuit target P80 is often an effective choice for these purposes.Any energy expended on “fines” is wasted. It also generates “extreme fines” often detrimental to downstream processing (McIvor and Finch, 1991). Only the portion of the mill power draw that is expended on coarse material is effectively used. This portion can be estimated from the mill feed and discharge size distributions (McIvor, 1988a) by taking the average of the percentage of “coarse” material in the mill feed and discharge. We can define the thusly calculated percentage of the mill power that is expended on coarse material in the mill as the ball mill circuit “classification system efficiency” (CSEff). The “effective mill power” (EMP) can be calculated from the total mill power (TMP) as follows."

Jan 1, 2007

By H. A. Wheeler

IT may surprise some of our members to learn, among the industries based on the mineral resources of the United States that of clay now ranks third, being exceeded in value of product only by pig-iron and coal. The present annual value of clay-products exceeds the value of the outputs of gold and silver, and also exceeds the combined values of copper, lead, zinc, aluminum, mercury, antimony and nickel. These facts are shown in Table I. which gives the statistics for the year 1902

Jan 1, 1905

By Helênio Resende Silva Júnior

PT. Krakatau-POSCO coke making plant, located in Cilegon, Indonesia, is the results of the know-how and experience of Paul Wurth (PW) in coke making field. The plant has a capacity of 1,321,000 t/y of gross coke achieved by two coke oven batteries with 42 top charging Paul Wurth “Jumbo” ovens each. PW “Jumbo” oven with a useful volume of 78,92 m3 allows decreasing drastically the number of pushing/charging operation per day with a consequent reduction of the diffuse emissions. Gas treatment plant with a capacity of 88000 Nm3/h has been designed in collaboration with DMT GmbH & Co. KG, adopting the latest technologies with specific design know-how. PT. POSCO-Krakatau plant has been successfully commissioned and started-up in October 2013. The present paper will highlight the main technology features applied in PT. Krakatau-POSCO project for both coke oven and gas treatment plants.

Aug 17, 2017

By J. E. Dutrizac, J. B. Sunstrum

Until relatively recent times, virtually all gold was recovered by gravity and/ or amalgamation methods. Although such techniques are very effective on coarse gold, they become increasingly less useful for finer grains especially when the gold is partly enclosed in rock matrix. Throughout the nineteenth century a number of bonanza gold fields were found in the United States, South Africa, Australia and Canada. In every case the abundant supply of gold nuggets and coarse alluvial gold soon gave way to hard rock mining with its inevitable losses of fine gold in the stamp mill tailings. Continuing efforts to develop new technologies capable of dissolving gold from finely ground ore were eventually successful first with chlorination (the Plattner process) and subsequently with cyanidation. Even before the nineteenth century, however, European chemists such as Scheele and Berthollet were aware that gold could be readily dissolved in an excess of free cyanide(1). As early as 1840, a patent was issued to the Elkington brothers for the dissolution of pure gold in cyanide solution and its subsequent plating onto various metals, with or without an applied electrical current. In 1846, Elsner showed that oxygen was also required to solubilize gold or silver in cyanide media(1). Despite the fact that much work was done on the reaction of cyanide solutions with gold, a viable leaching process for gold ores did not quickly emerge although cyanide solutions were used to enhance amalgamation from the 1860s onward. Major problems were associated with the use of concentrated cyanide solutions; the costs of cyanide were excessive and it was difficult to recover gold from the concentrated media.

Jan 1, 1999

By E. Wraith, W. W. Culver, B. Wesstrom, P. J. Mackey

Electrodeposited copper of the 1860s was of unprecedented purity, although the profound significance of this achievement was not fully realised until the dawn of the electrical age a decade or so later. By the 1870s there were three somewhat large (4 to 4.5 tonnes Cu/day) electrolytic copper refineries in Germany based on J. B. Elkington’s process, first patented in the United Kingdom in 1865. More such refineries were planned throughout Europe. At the same time, copper output in the U.S.A. was starting to expand and with the spread of European electrolytic copper refining technology across the Atlantic, the door opened to major increases in North American output. The technology was first taken up in 1879 by James Douglas at the Chemical Copper Company in Phoenixville, Pennsylvania, where he was Superintendent. Douglas was assisted in this pioneering work by Edward Weston. The copper refinery at the Chemical Copper Company was small, not unlike the first plants in Europe. The present authors contend that the electrolytic copper refinery at the Chemical Copper should be regarded as the first copper refinery in the United States. The Balbach Copper Refinery in New Jersey, which commenced operations in 1883 with an initial production of about 2 tonnes Cu/day, has been erroneously considered as the “first commercial refinery”; it rightly belongs in second place. The early developments at these plants are discussed in this paper. INTRODUCTION In the mid-1800s, the main uses for copper were as sheathing on the wooden sailing ships of the day to protect from marine growth, boiler components in locomotives and steam engines, along with some construction uses. Copper ores were generally smelted, and further fire-refined for market. The recovery of gold and silver, if present in payable amounts, was a slow and relatively expensive step. This situation regarding copper would change by the 1870s with advances in the generation and use of electricity. The introduction of the dynamo led to major developments in electrorefining. First demonstrated in principle by Faraday in 1831 (Faraday, 1832), the dynamo was subsequently adapted and further developed by J.S. Woolrich for electro-metallurgical applications in 1842 (Woolrich, 1842; Napier, 1845). It provided a new source of power with the unprecedented potential to significantly change the scale of metal production by electrometallurgy. Interestingly enough, copper would be needed for the electrical age just beginning. By 1869, advances in dynamo design offered relatively reliable large machines, which enabled J. B. Elkington in the United Kingdom to use the dynamo in the radically new Pembrey copper electrorefinery — the first copper electrorefinery in the world (Wraith, 2013). Initial production at Pembrey was small — in the range of 1 to 2 tonnes/day — while gold and silver were recovered more readily by the treatment of the slimes than with methods used hitherto.

Jan 1, 2019

By E. G. Kearnery

Introduction It is believed that the present paper will be of some interest, not because of any outstanding features of Renabie milling practice but because Renabie is the first gold mining property in a newly explored area - in Leeson and Rennie townships, Sudbury district, Ontario - to reach the production stage. The Renabie mill was originally designed by the General Engineering Company (Canada), Limited, as a 300-ton plant and went into operation in June, 1947, treating an average of only 128 tons a day for the balance of that year. Toward the end of 1948 the capacity of the plant was expanded to 450 tons a day, and the tonnage treated was gradually increased from the 1947 figure to the point where 420 tons a day was averaged for the first nine months of 1949. Description of Ore In general, the outstanding gangue component of Renabie ore is white quartz, which comprises at least 80 per cent of its total bulk and in some sections considerably more. Virtually all the gold occurs in very finely divided state; only very rarely has free gold coarser than 325 mesh been observed. The ore has a very low sulphide content, ranging from about 0.50 to 1.00 per cent by weight. The gold occurs both free in the gangue and ? locked in sulphides, the proportion of one to the other varying considerably from one orebody to the other. Pyrite is by far the most abundant sulphide, followed by galena, which, however, appears to be entirely absent in some of the orebodies. Minor amounts of pyrrhotite, chalcopyrite, chalcocite, and sphalerite have been noted. The ore appears to be entirely free, or almost so, of minerals containing arsenic, antimony, or molybdenum, and in general it could be described as free milling. The various hindrances to extraction of the gold which have been met with are believed to be due largely to the very finely divided state of the metal and to its intimate association with the sulphides and gangue. The ore contains silver, with the gold-silver ratio about 3:1.

Jan 1, 1950

By Ron Zevenhoven

In Finland one opportunity for large-scale CO2 capture, utilisation and storage (CCUS) is CO2 mineralisation, i.e. mineral carbonation. A process route under development towards industrial application involves production of magnesium hydroxide or sulphate from serpentinite rock (serpentine = 3MgO·2SiO2·2H2O), followed by conversion either in a pressurised fluidised bed (PFB) reactor, giving magnesium carbonate, or in an aqueous solution process giving magnesium hydro-magnesites. Iron present in the rock is typically obtained FeO(OH). Results obtained with these process routes and progress towards industrial demonstration is addressed, process heat integration and operation on flue gases (without CO2 pre-separation!) being key features for economic viability. A process route utilizing calcium-containing slag by-product from iron- and steelmaking under development towards large-scale application is the so-called slag2pcc concept. It converts an industrial by-product into valuable material, reduces use of natural material and streams to landfills while binding CO2 produced by the process generating the slag. Using ammonium salts, calcium is extracted from steel converter (BOF) slags and subsequently carbonated in a two-stage aqueous process (at ambient temperatures and pressures). Precipitated calcium carbonate (PCC) is produced while regenerating the ammonium salt. Process performance and scale-up while guaranteeing a certain PCC quality are presented.

Jan 1, 2015

By RICKARD HANSEN

With vehicles frequently found in mines and tires being a major fuel item, the risk of tire fires will be severe underground. This study presents an analysis of tire fires on mining vehicles to increase the knowledge of the risk and mitigating measures, which would improve the fire safety underground. Data from fire experiments and computational fluid dynamics (CFD) simulations were applied. It was found that the wheelhouse of a loader caused an increase in the flame tilt angle, decreasing the flame impingement and heat flux downstream. The flame temperature of a drilling rig tire was found to be higher than that of a loader tire, increasing the risk of igniting items. The construction of the wheelhouse/mudguard will contribute to a longer flame length by creating a fuel-rich environment. The CFD simulations predicted higher flame tilt angles for a drilling rig for higher flow velocities, indicating the influence of the wheelhouse/mudguard construction and tire geometry on the flame tilt angle. The construction of a loader resulted in flow behavior, where the short distance to the front mudguard/tire and the separation of flow directly downstream of the construction led to gases being steered past the front mudguard/tire. In a drilling rig case, the longer distance to the front mudguard/tire led to gases being directed toward the body of the vehicle after passing the area with flow separation.

By RICKARD HANSEN

With vehicles frequently found in underground mines and tyres being a major fuel item, the risk of tyre fires will be severe underground. This study presents an in-depth analysis of tyre fires on mining vehicles to increase the knowledge of the risk, applying data from full-scale fire experiments and CFD simulations. It was found that the wheelhouse of the loader caused an increase in the flame tilt angle of approximately 10%, decreasing the flame impingement and heat flux downstream. The flame temperature of the drilling rig tyre was found to be approximately 7% higher than the loader tyre, increasing the risk of igniting adjacent fuel items. The construction of the wheelhouse/mudguard will contribute to a longer flame length by creating a fuel-rich environment. The CFD simulations predicted higher flame tilt angles for the drilling rig case for higher flow velocities, indicating the influence of a varying wheelhouse/mudguard construction and tyre geometry on the flame tilt angle. The construction of the loader resulted in a flow behaviour, where the short distance to the front mudguard/tyre and the separation of flow directly downstream of the protruding construction led to fire gases being steered past the front mudguard/tyre. In the drilling rig case, the longer distance to the front mudguard/tyre led to fire gases being directed towards the body of the vehicle after passing the area with flow separation. An increased knowledge of the tyre fire risk on mining vehicles and mitigating measures would improve the fire safety in underground mines.

Feb 10, 2022

IF lead be heated with concentrated sulphuric acid two distinct actions will usually be observed. In the first, bubbles begin to be evolved more or less rapidly from the lead, and in the second, which occurs at a higher temperature than the first, hydrogen and sulphur dioxide are evolved, free sulphur is liberated, and leadsulphate is formed. The second action may be violent and usually continues till the lead is all consumed.Attempts have been made to apply these reactions, by means of a standard procedure, as a "Flash test" for the acid resisting qualities of chemical sheet lead. The purpose of this article is to comment on the best method of performing the test, on the various phenomena which may be observed during the course of it and on the interpretation of the results when obtained.PREVIOUS WORKIn 1919, Barr...

Jan 1, 1930

By G. M. Brownell

Introduction The Flin Flon mine is located on the boundary line between the provinces of Manitoba and Saskatchewan at a point about four hundred miles northwest of Winnipeg. A branch of the Canadian National railway provides the town of Flin Flon with direct transportation facilities. The property was staked in 1914 and, after a considerable amount of exploration; the Hudson Bay Mining & Smelting Company was organized and brought the property into production in November, 1930 (1). Mining is carried on by open pit and underground methods at the rate of about 4,400 tons per day. Production for the year 1934 was: 99,334 ounces of gold; 1,335,319 ounces of silver; 37,486,054~pounds of copper; and 49,427,280 pounds of zinc; in addition to small amounts of cadmium and selenium. The Flin Flon deposit is one of the largest low-grade ore deposits in Canada with complete hydro-electric and metallurgical plants for the production of blister copper and electrolytic zinc. Previous Work The development of the Flin Flon mine into one of the major mining operations in Canada has created a need for a more detailed geological study of the area. Practically all of the information published to date concerns the general surface features. It is the purpose of this paper to deal more specifically with the ore-body and its relationship to the enclosing rock as revealed by studies made possible through recent underground development. The earliest published report on the area is by E. L. Bruce (2), who made a reconnaissance geological investigation of the region for the Geo-logical Survey of Canada in 1914 and established the main. petrological units. Several years later the area immediately around Flm Flon was mapped in greater detail by F. J. Alcock (3). In the summer of 1934, the area of Missi sediments to the north and east of the mine was studied by J. W. Ambrose. His report has not yet appeared in print but his findings are of importance.

Jan 1, 1935

By John D. Carr

Introduction The Flin Flon zinc plant operates on what is known as the low density or standard sulphate process, that is, the zinc is carried through the plant solution circuit attached to the SO4 or sulphate radical at a concentration not exceeding 175 grams per litre zinc. The process may be described briefly as follows: The zinc is received in the zinc concentrate chemically combined with sulphur and mixed with many other impurities. The concentrate is roasted and most of the sulphur is burned to a gas, which is discharged from the plant. The roasted concentrate, or calcine as it is called, is leached with a weak sulphuric acid solution so that the resulting leach solution contains a high zinc content but a very small proportion of the impurities. The solution is separated from the solids and is purified further by agitation with zinc dust to remove copper, cadmium, and cobalt. This purified zinc sulphate solution is then pumped to the electrolytic department. The solids from the first leach are again leached, but this time with a stronger acid solution to dissolve all of the remaining zinc which is soluble in the strength of acid available. The solids and solution from the leach are then separated. The solids are stock-piled for further treatment at some future date and the solution, carrying a relatively high amount of impurities, is sent to the first leach, where the chemical action is such that the contained impurities are precipitated as solids. The electrolytic department is nothing more than a large number of electroplating cells in which the zinc is plated on aluminium sheets. Since zinc does not plate tightly to aluminium, the zinc plating or sheet is easily stripped from the aluminium and the sheets are collected to be melted and cast into the standard market bars or slabs. In the electro-deposition cells, the zinc sulphate (ZnS04) is split to metallic zinc (Zn) which plates out, and sulphate (S04) which combines with the hydrogen of the water of the solution to form sulphuric acid (H2S04). When one pound of zinc is deposited, about one and one-half pounds of sulphuric acid are formed. This acid is sent to the leaching section, where it dissolves one pound of zinc from the calcine. The solution is purified and is again pumped to the plating cells. The solution travel forms a complete circuit.

Jan 1, 1935

By J. Drelich

The flotation limit of fine particles has been re-examined based on the effect of bubble size on contact angle, and a new surface chemistry-limited relationship describing the minimum particle size which can be floated is proposed. In this analysis the critical value of bubble-solid contact radius (re) for which there is no effective attachment between particle and bubble has to be determined. The values of re determined by extrapolation of our experimental data for contact angle versus bubble-solid contact diameter permit the prediction of the flotation limit of methylated quartz particles, with fraction-al coverage of trimethylsilyl groups from 0.07 to 0.51. The limit of fine particle flotation as determined by this theoretical approach agrees well with experimental data reported in the literature.

Jan 1, 1994

By F. Baczek, S. S. Rocks, D. Chaiko, T. Walters

The atmospheric leaching of chalcopyrite concentrates using acidic ferric sulfate lixiviants is well known to suffer from slow leach kinetics and poor copper recoveries. A number of approaches have been proposed for improving both leach kinetics and recoveries in this system. Many of these, while effective, suffer from high CAPEX and/or OPEX. As many mine sites begin transitioning from heap leaching of copper oxides to processing of primary copper sulfides, cost-efficient leach processes that are compatible with existing SX/EW processes will be needed to maintain existing cathode production. To this end, FLSmidth is exploring process options and reactor technology for the hydrometallurgical processing of primary sulfides. One approach that appears to be highly effective at increasing copper recoveries takes advantage of the enhanced reactivity of transitory, surface-defect structures generated during particle fracture. Significant process efficiencies are gained by matching the rate of grinding to the rate of electrochemical leaching in Mechano-Chemical leach processes. The patent-pending FLSmidth® ROL process uses a Stirred Media Reactor (SMRt reactor) to achieve copper recoveries of 97+% in 6 hours or less. This approach overcomes many of the surface passivation problems that have hindered other atmospheric leach processes. New insights to leach mechanisms are presented.

Jan 1, 2015