The rapidly declining quality of ores and concentrates produced by Lubin Concentrator (KGHM) makes the flotation concentrates exceptionally difficult-to-process by flash smelting. Currently, a hydrometallurgical process, using sulfuric acid with the presence of oxidants as a leaching medium, seems to be either a reasonable alternative or a complementary option to pyrometallurgy. The unique lithological, mineralogical and chemical properties of the concentrate were considered in a selection of the process route. Results of a pressure leaching of the copper sulfide concentrate from Lubin Concentrator (ZWR Lubin) with oxygenated aqueous H2SO4 solutions are presented. The effect of temperature from 120 to 200 degrees C, initial concentration of H2SO4 from 60 to 100 g/dm(3), and oxygen partial pressure ranging from 0.5 to 2.0 MPa were investigated. The pressure leaching appeared to be an efficient process for recovering copper from the Lubin concentrate. At optimal leaching conditions (140 degrees C, 100 g/dm(3) H2SO4, 1.0 MPa 02) 96% of Cu was extracted after 4 h.

Recovery of silver and lead by means of chloride leaching of solid residue after atmospheric leaching of the copper concentrate from Lubin Concentrator (KGHM) was investigated. The effect of leaching temperature, chloride concentration, Fe(III) and oxygen presence, solid-to-liquid ratio and feed preleaching with NaOH on the silver and lead recovery was analyzed. Chloride leaching appeared to be very effective for recovery of lead, whereas satisfactory recovery of silver was observed after chemical pretreatment of the leaching feed with alkali solution of NaOH in order to liberate Ag entrapped in the jarosite structure. It was found that to achieve the satisfactory recovery of Ag and Pb leaching had to be performed in acidified 4 M chloride concentration at temperature of 90 degrees C. The presence of oxidants, that is O-2 and iron(III) ions, was beneficial in the initial stage of the process. The maximum recovery of Ag and Pb was found for the solid-to-liquid ratio of 1:10 after 10 hours leaching.

Cobalt is recognized as a strategic metal and also E-tech element, which is crucial for worlds development. An increasing demand for cobalt forces for searching of new resources that could be explored in European countries. There are many examples of cobalt recoveries, mostly from laterite and sulphide deposits. However, the accurate choice of the technology depends on many factors. The Kupferschiefer stratiform copper ore located in Poland is the biggest deposit of cobalt in Europe. Although KGHM Polska Miedz S.A. recovers many precious metals from this ore, cobalt is not recovered yet. This metal occurs as an accompanying element, mostly in the form of cobaltite (CaAsS), with the average content of 50–80 g/Mg. In this paper a possible recovery of cobalt from the Kupferschiefer ore, with the use of hydrometallurgical methods, was investigated.

Rapidly declining quality of copper concentrates produced by Lubin Concentrator of KGHM Polska Miedz SA, having very low content of Cu, high content of Pb, As and organic carbon as well as significant contents of Ag, Co, Ni, Zn, Re, V and Mo, makes the concentrates difficult-to-process by flash smelting. Currently hydrometallurgy, using sulfuric acid in the presence of iron(III) and oxygen as a leaching medium for base metals and chloride leaching for silver and lead, seems to be an alternative for pyrometallurgy. The goal of the work is to discuss main aspects of the necessity of application a new hydrometallurgical technology, based on different unit operations, including non-oxidative atmospheric, chloride and pressure leaching, recovery of Pb and Ag, separation of Cu and accompanying metals from PLS and arsenic neutralization. The unique lithological, mineralogical and chemical properties of the process feed were discussed in details. The results of laboratory investigations performed at the Wroclaw University of Technology and assumptions of the process scale-up for acquisition of data for full scale technology were summarized. Planned investigations on the pilot plant scale will provide technical and economic data for a pre-feasibility study of the future hydrometallurgical plant.

An experimental study on leaching of cobalt and nickel from a Lubin (Poland) sulfide flotation copper concentrate with oxygenated sulphuric acid solution in the presence of iron(III) sulfate is presented. The effect of temperature, iron(III) concentration, initial sulphuric acid concentration, oxygen flow rate and chloride ions addition on cobalt and nickel leaching were examined. The obtained results show, that enhancing investigated leaching parameters increases both the rate and leaching recovery of nickel and cobalt. The effect of iron(III) ions concentration is particularly significant. Additionally, a significant correlation between copper and nickel/cobalt leaching recovery was observed. Due to the fine dissemination of nickel and cobalt, they were leached remarkably faster when copper leaching recovery exceeded 90%.

Hydrometallurgical recovery of silver from a solid residue after pressure leaching of a flotation copper concentrate from the Lubin Concentrator (KGHM Polska Miedz S.A.) was investigated. Thiosulphate leaching was examined with regard to the highest possible leaching efficiency and optimization process parameters. The effect of thiosulfate ions concentration within the range from 0.25 to 1.00 mol/dm(3) at a constant ammonia concentration, and ammonia concentration within the range from 0.40 to 1.00 mol/dm(3) at a constant thiosulfate concentration on leaching recovery of selected metals were examined. Moreover, the effect of copper(II) ions addition on silver leaching was studied. It was shown that the leaching recovery of silver increased with increasing thiosulfate and ammonia concentration. At the highest thiosulfate ions concentration, the observed silver leaching recovery was 60%. The best results were obtained at an ammonia concentration of 0.80 mol/dm(3), where the leaching recovery of Ag reached 75%. It was established that addition of Cu(II) did not affect silver leaching. Nearly 100% efficiency of thioslulohate silver leaching was achieved by pretreatment of the solid residue after pressure leaching with NaOH solutions.

In a present paper the results of pure metallic silver electrochemical recovery from the solution obtained by two-steps of chloride leaching process of Lubin, Poland copper flotation concentrate are discussed. Potential-controlled electrolysis (PCEl) was used as a promising method of silver electrochemical recovery from low concentration complex composition aqueous solutions. The studied solution contained approximately 50 mg/L of silver. The electroreduction of silver was studied using cyclic voltammetry and chronoamperometry in two and three electrode configuration systems. The effect of several factors such as potential, time of electrolysis on selectivity of silver reduction was studied. Based upon conducted experiments the conditions of pure silver powders cathodic electrodeposition using PCEl method were determined.

A series of laboratory experiments have been performed on pressure leaching in oxygenated sulphuric acid solutions of commercial copper flotation concentrate produced by Lubin Concentrator (KGHM, Poland). Major copper sulphides: chalcopyrite, bornite and chalcocite were reported to undergo phase conversion to covellite (CuS), which was found to be the most stable sulphidic form of copper. The formation of copper sulphide (covellite) appeared to be a significant step in the examined pressure leaching process. Copper present in the flotation concentrate was observed to be solubilised in the leaching solution only after the conversion of all copper sulphide minerals into the covellite phase. Permeable, openwork texture of covellite formed during the copper sulphide conversion facilitates easy leaching and transport of the leaching medium to the leaching surface, effecting leaching of the remaining minerals in the solid feed.

Hydrometallurgical treatment of complex copper sulfidic ores, by-products and concentrates requires aggressive, oxidative leaching methods and application of Fe(III) ions and oxygen or bacteria assisted environment. Leach liquors generated in the process are usually copper and iron-rich solutions of high acidity. Such conditions require the application of suitably strong and selective reagent to extract copper in SX operations. This paper discusses the copper extraction behavior of commercial copper rea- gents: LIX 984N, LIX 612N-LV and Acorga M5640. Aqueous feed solutions used in SX studies were PLS' generated in atmospheric leaching of commercial flotation concentrate, produced at Lubin Concen- trator (KGHM). McCabe-Thiele diagrams were generated and copper net transfer values were compared and discussed. It was shown that stronger modified aldoxime reagents (Acorga, LIX 612) are superior over non-modified salicylaldoxime/ketoxime mixture (LIX 984N). Particularly, the ester modified Acor- ga M5640 showed advantages in recovery and copper net transfer values.

Systematically shrinking copper resources and remarkably declining copper ores grade leads to the growing role of hydrometallurgical processes in manufacturing copper and accompanying metals. Technical, economical, and ecological aspects of application of hydrometallurgy were discussed with regard to dominating smelting methods. Specific conditions of in the Polish copper industry were evaluated and important aspects of necessary application of hydrometallurgy at KGHM for more effective processing of copper ores and concentrates were indicated. The hydrometallurgical unit operations compulsory in unique conditions of Polish copper industry: high content of carbonates, decreasing content of Cu, and increasing content of Pb, As, and organic carbon were analyzed. Hydrometallurgy was recognized as the only real chance for more rational utilization of metal resources from the Polish copper deposits. The advantageous chemical and mineralogical composition of Polish copper ores and concentrates and easy access to sulphuric acid additionally substantiate the need for comprehensive research work.

Recently, very unfavorable trends of decreasing copper content and increasing complexity of the Polish copper ores as well as lowering quality of final concentrates and metals recovery from concentration plants have been observed. This is also a major problem for the Polish copper smelters, which capabilities are not adapted to the complex and declining deposit conditions. The solution of this problem should be sought in hydrometallurgical methods (Leach-SX-EW). This paper focuses on the role of solvent extraction (SX) in recovering valuable metals from pregnant leach solutions. The problems related to the separation of undesirable and toxic metals are also discussed.

Measurements of the rest potential of copper sulfide electrodes and pyrite, present in copper ores and concentrates from Lubin Concentrator, have been carried out. Moreover, measurements of sulfide-sulfide contact potential and galvanic current were also performed using deoxygenated sulphuric acid solutions as well as the solutions saturated with oxygen and containing Fe(III) ions. Significant galvanic interactions were observed for sulfide couples exhibiting high potential difference, particularly when copper sulfides were short-circuited with pyrite. According to mineralogical data for Lubin polymincral copper concentrate, chalcocite and bomite are dominating with chalcopyrite and covellite as minor copper minerals. Expected is advantageous affect of pyrite in promoting the kinetics of copper leaching from Lubin concentrate as a result of observed galvanic interactions between pyrite and copper sulfides.

Results of atmospheric leaching of copper sulphide concentrate from Lubin Concentrator (ZWR Lubin) with oxygenated aqueous H2SO4 and in the presence of Fe(III) have been presented. It was found that oxidative atmospheric leaching performed in acidified and oxygenated iron(III) solutions has to be preceded by a controlled, non-oxidative decomposition of acid-consuming carbonate components in order to further liberate finely disseminated metal-bearing minerals. Atmospheric leaching appeared to be a very efficient process for recovering Cu, Zn, Co and Ni from the Lubin concentrate due to favorable mineralogical composition and fine size of leached particles. A maximum recovery of Cu (95%), Zn (90%), Ni (40%) and Co (50%) was observed after 5-7 hours of leaching at 90 degrees C in the oxygenated solutions containing 20-30 g/dm(3) of Fe(III). The solid residue after atmospheric leaching will be further processed by flotation or chloride leaching to recover Ag, Pb and precious metals.

Presented are the results of laboratory investigations on pressure leaching of copper sulphide concentrate produced at Lubin Concentrator (KGHM Polish Copper). Elevated content of base metals (Co, Ni, Zn, As, Ag, Pb) and of organic carbon was the specific feature of the concentrate. High content of cobalt and zinc, high content of Pb and As and the concentration of organic carbon exceeding 10 % make this concentrate both unique and hard to process by means of flash smelting. Alternative, hydrometallurgical method of Lubin concentrate processing is currently seriously considered. The effect of initial temperature, concentration of sulphuric acid, and oxygen partial pressure on leaching rate and metals recovery has been investigated. Leaching was performed in a stirred autoclave at temperatures within the range of 120 - 180 oC. Oxygen at partial pressure from 5 to 12.5 at was used as an oxidizing agent. It was found, that consid-erable increase of the leaching rate and recovery of copper can be observed with in-creasing both temperature and oxygen partial pressure. The recovery of cobalt and nickel was evidently lover. SEM microscopy examinations were performed for solid residue after leaching in order to explain observed leaching kinetics.

Simultaneous measurements of pH and redox potential using a platinum electrode as well as potential of copper sulphide electrodes during non-oxidative leaching of Lubin shale middlings with sulfuric acid have been applied to determine leaching kinetics and to evaluate its electrochemical parameters as well as to assess the changes taking place at the mineral/solution interface during leaching process. Significant decrease in both redox potential of the solution (from +350 mV to +50 mV, Ag,AgCl) and potential of mineral electrodes were observed with increasing pH during carbonate decomposition with sulfuric acid. It is therefore concluded that the low value of red-ox potential is a parameter preventing oxidation of copper sulphide minerals present in leached material and prevents the transition of Cu and Fe to the solution. It was found that the non-oxidative leaching is a rapid and selective process, resulting in decomposition of calcium and magnesium carbonates and in saturation of the leaching slurry with carbon dioxide. It was recognized that with the increasing degree of carbonate decomposition from 50 to 100 % metalsbearing minerals liberation has remarkably improved, which beneficially facilitates and intensifies further upgrading or leaching processes.

Ammonia pressure leaching has been investigated as an alternative for hydrometallurgical processing of Lubin middlings - a shale-enriched flotation by-product. The effect of primary parameters: temperature, oxygen partial pressure, ammonia and ammonium sulfate concentration and stirring rate on leaching recovery of Cu, Ag, Zn, Ni, and Co were examined.

Ammonia has been widely applied as an effective leaching agent in numerous hydrometallurgical processes for many years. Ammonia can be effectively used for leaching of base metals (Cu, Ni, Co, Zn) as well as for precious metals (Ag, Au) because of formation of soluble, very strong ammonia complexes. Moreover, ammonia has been considered as an attractive leaching agent due to its low toxicity, low costs and ease of regeneration by evaporation from alkaline solutions. An important advantage of ammonia environment in hydrometallurgy is its selectivity in terms of solubilization of desired metals and precipitation of undesirable iron in one unit operation (Meng and Han, 1996). Ammonia leaching can be used in non-oxidative, oxidative and reductive leaching. It was first applied and developed for recovery of copper from its metallic and oxide raw materials. Copper forms well soluble and very stable complexes ([Cu(NH3)4] ) and can be leached at ambient conditions due to the excellent solubility of ammonia in water. _________

Heap leaching of oxide copper ores and cathode copper recovery by solvent extraction (SX) and electrowinning (EW) has been well established as a primary low-cost hydrometallurgical copper recovery method. Subsequently, hydrometallurgy was also gradually developed and applied for sulphidic ores and concentrates. Presently, more than 20% of total world production of copper is achieved through the solvent extraction route. The success of this method led to a significant revival in the development of hydrometallurgical processes to recover copper from ores both sulphidic and oxidized. This work reviews the major problems related to solvent extraction from pregnant leach solutions (PLS) after leaching oxide and sulphide copper minerals.

The beneficial effect of leaching of carbonate gangue from flotation middlings and rougher concentrates with sulfuric acid prior their final flotation has been presented. This process was effectively applied within the existing flotation circuit in order to facilitate floatability of difficult-to-treat carbonate black shale copper ores. The leaching of flotation feed with sulfuric acid selectively decomposes the carbonate gangue and leads to selective liberation of sulfide minerals, enhancing flotation results. It was shown, that after leaching out of 50–70% of carbonates from flotation feed, both flotation recovery and concentrate grade increased considerably in relation to results observed for unleached feed. The products of acidic leaching comprise gypsum, soluble magnesium sulfate and gaseous carbon dioxide. Carbon dioxide evolving during the reaction favorably creates the non-oxidizing atmosphere in the pulp during leaching and effectively prevents the digestion of metals from sulfide minerals. The beneficial effect of acid leaching on flotation was evidently confirmed during the pilot tests performed on several feed materials. The application of sulfuric acid leaching for flotation feed resulted in pronounced enhancement of flotation results (both metal recovery and concentrate grade) and could provide a rational use of H2SO4, particularly if it becomes a troublesome and difficult-to-sale product of copper metallurgy. Recently, the sulphuric acid prices are rather high.