Search Documents

By Kazuki Morita

Dissolution mechanism and solubility of chlorine in the oxide melts, such as CaO-SiO2-Al2O3 (-Na2O), Na2O-SiO2-Al2O3 and CaO-SiO2-FeO systems, have been equilibrium technique was employed with controlled Po2 and PCl2, (Po2 = 10-6 -10 19 atm, PCl2 10-6 -10-13 atm at 1673-1748 K). The solubility of chlorine in the 40mass%CaO-40mass%SiO2- 20mass%Al2O3, slag was found to vary in proportion to Pb2/ w and pc/z/p' which proved that chlorine dissolved in the melts as C1 anion. Hence, the chloride capacity (CCI-), indicating the ability of molten oxide to absorb chlorine, has been defined as; The Ccl value was observed to increase with increasing slag basicity and temperature, and showed a reasonable relationship with that Of CS2-. Based on the result obtained in the present study, chlorine distribution during incineration with slags was predicted quantitatively.

Jan 1, 2003

By A. N. Zagorodnyaya, T. N. Bukurov, Z. S. Abisheva, A. S. Sharipova

"The paper describes the results of stripping of copper production dusts by leaching with aqueous soda, nitric acid solutions and recovery from solutions resulting in the production of lead sulphate, tribasic lead sulfate (TBLS), ammonium perrhenate, zinc, copper-cadmium cake.The combination of two stripping operations under chosen optimal conditions allows the recovery of 98% rhenium, 82% lead, 92 % copper, and 96% zinc and cadmium each. The major amount of rhenium (~ 80%) is recovered at the carbonization stage, and other metals - at the nitric acid leaching stage.Lead sulfate was precipitated by mixing solutions resulting from carbonization and leaching. Tribasic lead sulfate was produced by dissolving lead sulfate in sodium hydroxide solutions. Rhenium was recovered from mother liquor resulting from lead sulfate precipitation by liquid-liquid extraction and zinc was recovered from raffinates. Trialkylamine (TAA) was used as an extractant for rhenium recovery and di-2- ethylhexylphosphoric acid was used for zinc recovery. Optimal liquid-liquid extraction parameters have been defined allowing the recovery of 96% rhenium in crude ammonium perrhenate and 94% zinc in sulfuric acid solution. Based on the experimental data, the flowchart for dust processing to produce salable products - lead, rhenium, zinc salts has been suggested."

Jan 1, 2003

By Kazuyuki Kakegawa

The sintering characteristics and the change in the compositional distribution in the PbTiO3 PbZrO3-Pb(Mgl/3Nb2/3)O3 system during the sintering process by spark plasma sintering (SPS) method were examined. They were compared with those by a normal sintering method. The densification by the normal sintering was slow even at high temperatures, When SPS method was employed, much lower temperature and shorter period resulted in sintered bodies having almost the theoretical density. As expected in normal sintering, the compositional distribution decreased as the sintered density increased. On the contrary, the change in the compositional distribution by SPS was much smaller than that in the normal sintering. This sintering characteristic of SPS suggested a possibility of fabrication of sintered material having a desired compositional distribution.-

Jan 1, 2003

By Kari Moen, John Rasmus Leinum, Jarle Hjelen, Terje Malvik

"Industrial minerals may contain the same elements in approximately the same amount. In these cases backscatter electron imaging or chemical analysis are not sufficient to identify the minerals. Another problem arises when micro textures are not detectable in traditional imaging or the grain size is smaller than the X-ray spatial resolution.As a supplementary technique in these cases, application of crystallographic information by electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM) may be a suitable method. The technique has been demonstrated on three Norwegian mineral raw materials and one Italian marble and shows that it has some advantages compared to traditional techniques.• quantitative measurements by ebsdCommon automatic techniques describing the mineral contents and the occurrence of minerals in free and locked particles, are based on optical-, backscattered electron (BSE)- or X-ray-signals. There are various commercial software systems on feature analysis by backscattered and X-ray signals in combination with image analysis (e.g. Oxford Inca Feature, CSIRO QemScan).Especially in silicates, the occurrence of similar elements in the different minerals is common. Sometimes the various minerals not only contain the same elements, but also approximately the same amount of each element. In these cases BSE imaging and chemical analysis are not always sufficient for identification."

Jan 1, 2003

By R. M. Imhof, M. J. G. Battersby, J. V. Brown

There is a plethora of former industrial sites where coal mining operations have left large slurry impoundments. These contain raw washed fines, which have previously been too expensive to process to requisite grades for commercial use. New technology has been developed for fine material processing, namely the Imhoflot pneumatic flotation G-Cell. This froth flotation technique is a highly efficient means of concentrating coal and is particularly appropriate to the nature of materials encountered in tailings ponds. The high volumetric throughput resulting from the vastly reduced residence time in the cell allows for drastically reduced equipment sizes when compared to conventional flotation cells. This means the process, when combined with innovative pre treatment and filtration equipment can be developed as a mobile plant concept. This is seen as a minimum requirement when re-treating and rehabilitating fine coal ponds.

Jan 1, 2003

By S. K. Kawatra, S. J. Ripke, T. C. Eisele

"An estimated 600,000 tons of bentonite clay are used annually in the U. S. as binder for production of iron ore concentrate pellets. Since this is a significant cost item for the plants, and the addition of bentonite to the pellets contributes undesirable silica into the finished pellets, there is considerable incentive for finding methods to reduce bentonite use. One way to reduce bentonite levels is to selectively use those bentonites that are most effective in this application, so that a lower dosage will still produce a sufficiently strong pellet. Unfortunately, there are no satisfactory methods available for accurately predicting which bentonites are actually most effective, short of using them to actually make pellets. One of the popular methods for attempting to evaluate bentonites is the “Plate Water Absorption” (PWA) test. While some plant operators accept the PWA results as indicating the relative quality of bentonites, others disagree and claim that, over a fairly broad range of values, PWA does not correlate with bentonite performance.Since both Ca+2 and Mg+2 ions are known to reduce the swelling and water absorption capacity of bentonite, it was believed that the presence of these ions in plant recycle water could be changing the bentonite performance. Since the standard PWA test uses only distilled water for its measurements, it could not detect these effects. Experiments were therefore carried out on a number of different bentonites using a modified PWA tests, with plant recycle water replacing the distilled water. These experiments showed little effect of the plant water on the PWA value, and chemical analysis of the water showed that the levels of dissolved salts were quite low.Water and accompanying salts were then extracted from a magnetite concentrate filter cake by rinsing with distilled water. Analysis of this water showed an extremely high level of dissolved salts, particularly salts of calcium and magnesium. When concentrations were compared with the recycle water from the plant filters, it was determined that levels of Ca+2 and Mg+2 retained in the filter cake were over 500 times higher than levels in the recycle water. This extreme elevation of soluble salts in the filter cake is believed to be due to adsorption of these ions into the electrical double layer of the magnetite particles."

Jan 1, 2003

By Katsuyoshi Kondoh

The synthesis processing of Mg2Si or Mg2SiIMgO at lower temperature from the elemental magnesium alloy powder/chips and Si or SiO2 powder mixture was established via the repeated plastic working (RPW) based on Powder Metallurgy (PIM) process. RPW is much effective on the mechanical breakage of MgO surface films, which prevent from the solid-state reaction between Mg and Si powder. The solid-state synthesized Mg2Si particle of 200nm-2um is extremely fine, compared to that via the conventional casting process, causing the coarse one of 50-100um. This is because of not coarsening during the solid-state synthesis of Mg2Si. By using in-situ fonning process of Mg2Si via RPW and pre-heating before hot working such as extrusion and forging, the magnesium composite material with Mg2Si or Mg2Si/MgO dispersions was developed in employing Si or SiO2 particles, respectively. For example, when employing AZ31 chips as raw materials of the matrix, it has low density of 1.85g/cm3 and extremely superior mechanical properties, such as tensile strength over 350MPa with 5-10% elongation and Young's modulus of 47-50GPa, to the conventional Mg-Al-Zn alloys. The Mg composite alloy wires and pipes were produced via the hot extrusion process in the manufacturing plant, and also showed excellent mechanical properties.

Jan 1, 2003

By John J. Dunkley

Recent years have seen the increased use of hydrometallurgy in the smelting and refining of metals. However this is often used as a final refining step, following an initial pyrometallurgical smelting process. Huge amounts of material are produced as melts which have to be cast, comminuted, and taken up into solution or leached. A common method is to granulate the melt and then grind it. In the case of metallic melts this can be difficult or unfeasible due to the ductility of the granulated particles. Water atomisation is capable of replacing the granulation and grinding stages with a single process step that can process in excess of 30t/hour of melt into particles as fine as 50 microns. Applications in operation in Co, Cu, Ni, Ag, Au, Pt and Rh refining are discussed together with potential applications in copper smelting.

Jan 1, 2003

By Gerardo H. Achurra

During the last years, the Caletones Smelter, like others copper smelters in the world, has evolved from the conventional, inefficient, pollutant and expensive technologies, to modern, environmentally friendly and efficient ones. For this reason' as well as to improve its competitive position this Smelter shut down the reverberatory furnace, started up two big acid plants and has developed some pyrometallurgical technologies. The main facilities of the Caletones Smelting and Converting Process, in the present and the future, are the Teniente Converters, the reactors with a high operational availability that have reached concentrate top process capacities near to 2,400 tpd. These reactors operate in most of Chilean smelters as well as in other smelters in the world such as in Zambia, Peru and Mexico. Since 2000, the Caletones Smelting and Converting Process, has been adapted in two Teniente Converters, four Slag Cleaning Furnaces and four Pierce -Smith Converters. These facilities, together with the operation of two Fluidized Bed Dryers and two Oxygen Plants have allowed to reach concentrate smelting capacities and copper productions of 1,250 ktpy and 380 kfipy, respectively. Associated to EI Teniente Division Expansion Plan, Caletones Smelter, in the first stage, will increase its capacity to 1,440 ktpy in 2004. In the long term, Caletones has different options, such as the processing of 1,600 to 2,000 ktpy of concentrate, producing anodes, white metal or a mixture of them. These options are connected with CODELCO's Smelters & Refineries Strategic Plan, including Mejillones Project. The main challenges of Caletones Smelter are associated to the development and the consolidation of the Continuous and Environmental Friendly Processes, automation and control of different processes and to the improvement of its leadership between other Copper Smelters in the world.

Jan 1, 2003

By Ashok M. Raichur, S. P. Vijayalakshmi

"Recent advances in technology and the growing environmental concern have laid emphasis on the usage of fine clean coal. Coal fines are also generated in large amounts during various coal processing operations and are difficult to be treated, handled and disposed. Since most of the operations use water as the carrying medium, the fines so generated contain lot of moisture. Conventional technique for processing coal fines includes flocculation by a polymeric reagent followed by moisture removal using a rotary drum or a pressure plate filter, which produce a product with more than 30% moisture. Polymeric flocculants though required in small amounts, need high shear mixing for good performance and operate only in a narrow pH range. Moreover they increase the viscosity of the solution by many folds. Hence it becomes imperative to emulate newer methods for efficient fine coal processing. One such method is the novel use of microorganisms in coal processing.The present investigation deals with the utilization of two gram-positive microorganisms, Mycobacterium phlei and Bacillus subtilis, as bio flocculants and dewatering aids in fine coal processing. Preliminary characterization done on J-coal and M.phlei showed that they are negatively charged over most of the pH range. B.subtilis was found to possess positive charge below pH 4.7. The adhesion studies proved the high potential of microorganisms for adsorption to surfaces. Adhesion tests were conducted at various experimental conditions by varying parameters like pH and ionic strength of the suspension. Results obtained showed that adhesion is always higher in the presence of an electrolyte like KNO3 and most of the adhesion takes place in 15 minutes. With change in pH the amount of B.subtilis adhering on to J-coal remained almost constant and for M.phlei it decreased at higher pH values. Increase in ionic strength did not increase the adhesion of bacteria. Flocculation experiments confirmed the ability of the bacteria to act as bio flocculants. It was seen that about 98% of the coal settled in about 2 minutes on the addition of bacteria along with the addition of the electrolyte. The electrolyte was found to be indispensable for efficient flocculation of the coal suspension and for the attainment of a clear supernatant after flocculation. Also the optical micrographs revealed the formation of large, tight flocs when the electrolyte is present along with the bacteria. Further, flocculation tests were done in the pH range of 2-10 and the flocculation efficiency was found to be independent of pH."

Jan 1, 2003

By D. Berkley

"The competitive pressure, the increasing energy costs and the environmental regulations impose substantial challenges to the definition of power plants serving industrial facilities. Primary mining and metallurgical facilities have even greater challenges because they are often located remotely, where the fuel supply can be a problem. The absence of a power grid imposes challenges on the reliability and quality of the electrical energy supply. In addition, the facilities usually require thermal energy too, not only electricity.This paper outlines these types of issues that have to be considered when defining a cogeneration plant integrated with a remotely located industrial facility. It is addressed to the “users” of cogeneration facilities rather than to “generators.” The focus is on analyzing various site-specific design considerations to prescreen the feasible cogeneration alternatives and minimize the number of options to be analyzed from the economics viewpoint. This approach could substantially reduce the engineering effort and schedule during the feasibility phase of the project.The front-end of the paper provides a basic understanding of cogeneration plants of various types to establish a common language. Subsequently, the paper outlines and analyzes specific issues that could be of help in the definition of cogeneration installations for remotely located industrial facilities, with a focus on mining and primary metallurgical plants"

Jan 1, 2003

By Fumitaka Tsukihashi

Phase diagrams of the CaO-SiO2-FeOx-MgO, Al2O3 systems are necessary for the analysis of copper smelting reactions and sintering process of iron ore. The effect of MgO and Al2O3 addition on the liquidus of the phase diagram of the CaO-SiO2-FeOx system at low oxygen partial pressure was observed. The liquid phase area changed by the addition of MgO and Al2O3 with a changing oxygen partial pressure from 10-8 to 10-3 atm (10-1 to 102 Pa) at 1573K. The effect of Fe3+/Fe2+ ratio on the melting mechanism is discussed.

Jan 1, 2003

By Qiu Dingfan

The Slurry Electrowinning Process (SEP) is a new hydrometallurgical method and clean technology, Sulfide ores can be treated by the SEP without S02 emission and the sulfur from the sulfides can be recovered in element form which is easy to stockpile and can be transported at low cost. In a special slurry electrowinning cell one can achieve at the same time the leaching of elements from the feed and the electrowinning of metals from the electrolyte, Because the anode reactions are utilized for leaching of some elements the consumption of the energy is decreased, SEP also has the advantage of separation some elements, It is especially suitable for treatment of complex concentrates containing Pb, Cu, Au, Ag and S, which could hardly be accepted by any smelter. In this work, the behavior of different metals in this process has been studied and it was found that the separation of metals in some minerals is possible through the SEP, Beijing General Research Institute of Mining and Metallurgy (BGRIMM) has studied the possibility of the SEP to treat bismuth concentrates containing S, Be and F in laboratory and pilot-test scale as well as in commercial plants, The commercial plant was set up in 1997, It has been in operation since that time, According to the results of laboratory experiments and pilot- plant test, a new plant to treat complex gold minerals was set up in 1998 and is in operation in 1999

Jan 1, 2003

By G Johnson, G W. Wilson

The settlement and drainage behaviour of co-mix, or mixtures of waste rock and tailings, are examined in a column study. Three co-mix profiles were observed for settlement, drainage, and pore water pressure response. A fourth profile with waste rock and no tailings was also observed for settlement. Co-mix consolidated faster than predictions for tailings alone, and maintained a saturated void space relative to waste rock alone. Practical benefits of co-mix as a waste disposal technology may include faster time to consolidation than tailings, a reduction in total settlement of placed material compared to tailings alone, and a reduction in acid drainage by limiting the flow of water and oxygen through maintenance of a saturated void space.

Jan 1, 2003

By Philip J. Guerney, S. O’ Leary, André R. Laplante

"Concentration of dense mineral phases (s.g. greater than 7) for characterisation of individual particles and mineral grains by electron microscopy is a well established technique for the detection and characterisation of valuable mineral phases. This presentation describes the type of data that can be generated when both the concentration and characterisation steps are carried to higher levels than typical. The concentration step is the gravity recoverable gold (GRG) protocol that has been used for over 100 ore samples. This protocol yields three concentrates that represent three progressive degrees of grinding and liberation. Three ore samples were subjected to the GRG protocol and three size classes of each concentrate were characterised using the mineral liberation analyser (MLA), an automated, EDX-based tool. This presentation briefly presents GRG and MLA technology, and then focuses on the results obtained: photos, images and databank, the latter used to evaluate the extent of particle liberation and particle shape.INTRODUCTIONThe practice of gravity concentration prior to characterization of mineral samples using electron beam microscopy is solidly established. Typically, a dense liquid such as tetrabromoethane (density: 2.97 g/cm3) is used to reject the light phase, typically carbonates and silicates. The heavy phase, mostly sulphides, oxides and precious metals, is then mounted in a polymer matrix and examined using beam microscopy.Both the pre-concentration and the sample preparation/examination steps have seen significant advances over the past ten years, but are not without problems. A major issue of preconcentration is that most dense liquids used are toxic, tetrabromoethane being a prime example. More recently, a dense liquid with little or no toxicity (sodium polytungstate, distributed by Sometu Inc.) has become commercially available, but its use is limited to relatively low s.g. splits around 3 g/cm3. Dense liquids are viscous, and their use is limited to particles coarser than 37 µm, although centrifuge separation can probably lower this limit to around 10 µm. Magnetogravimetric separators can achieve much higher specific density cuts, but upgrading below 100 µm or in the presence of magnetic minerals remains a problem. The use of centrifuge separators such as the 3-in Knelson Concentrator (KC MD3) or the Falcon 4-in SB (SB4) is particularly attractive since these units can easily process large masses (by laboratory standards) and achieve a cut density well above those of dense liquids."

Jan 1, 2003

By E. V. Manlapig, M. C. Harris

"The complexity of the flotation process has made the identification of an appropriate model structure, for use in the prediction of flotation circuit performance, far from obvious. Work performed under the auspices of the AMIRA P9 flotation program has indicated that the metallurgical performance achieved from a flotation cell arises from the interaction of two essentially independent property classes, namely the cell operating conditions and the properties of the cell feed stream. These observations have led to the development of a model structure that associates a constant set of flotation parameters to the streams of the circuit, which are transformed into a flotation response depending on the operating conditions within the flotation cell.A variety of alternative model structures exist within the literature which do not make this distinction between cell and stream flotation properties, and many of these models are in widespread use for flotation optimisation and design studies, both in industry and academia.In this paper, data collected from an industrial flotation circuit is used to derive the parameters associated with two different types of flotation models. Simulations performed using these models demonstrate the need to differentiate between cell and feed properties. A model that does not differentiate between these two properties fails to successfully predict the metallurgical performance of a flotation circuit after a disturbance."

Jan 1, 2003

By J. B. A. Solar Menéndez, M. A. Martínez Fidalgo, L. A. Alvarez-Santullano

1. ANTECEDENTS This present communication refers to the results of the research project entitled "Training in the correct use of chemical oxygen self rescue apparatus and also an analysis of apparatus autonomy", carried out under the auspices of the Specific Collaboration Agreement signed between the Industry Council of the Principality of Asturias (Spain) and INSALUD (National Silicosis Institute, Spain). The antecedents of this project lie in work undertaken by the National Silicosis Institute aimed at optimising efficiency in the use of chemical oxygen self rescuers through improvements in worker training. To be precise, by means of Agreements drawn up between the above-mentioned parties, a simulator was designed and incorporated as the basis of a training station within the " Fundación Barredo" of the Industry Council of the Principality of Asturias. This has been operative since the year 2001 and, up to the present, 2300 Asturian coal mine workers have been trained there. What prompted this activity was the observation of various errors in the use of the self rescuers, deriving from their innate characteristics, especially with respect to the sensation of discomfort - the high temperature and humidity of the breathed oxygen, resistance and inconvenience - and limited autonomy. It was precisely this insight that, in critical situations, lack of familiarity with the conditions of discomfort likely to be experienced during the evacuation process might lead to rejection of the equipment, with fatal consequences, that has justified the setting up of this training and simulation centre. The centre is able to provide all mine workers with the necessary training, and experience of the characteristic sensations experienced when using such equipment (Fig.. 1).

Jan 1, 2003

By Mitsuru Tanahashi

In order to develop an effective process for the production of a solar-grade silicon (SOG-Si) from metallurgical-grade one (MG-Si), the oxidation removal of boron from molten MG-Si was investigated at 1773 K by the following two CaO-saturated CaO-CaF2 flux treatment processes. I) Boron removal by flux addition onto the molten MG-Si followed by oxygen gas injection into the melt (Two-stage connecting process). II) II) Boron removal by simultaneous injection of flux powders and oxygen gas into the molten MG-Si (Simultaneous injection process). These processes can establish the special condition of both high basicity of the flux and the high oxygen partial pressure at the boron removal reaction sites. Through these processes, especially by the simultaneous injection process using a flux powder injection equipment, the boron content in MG-Si can be efficiently reduced. The obtained results clarified that both processes should be conducted for a time period as short as possible by using as much flux as possible. By repeating the simultaneous injection process for 60 s three times under the optimum operating conditions determined in the present study, the boron content in MG-Si can be reduced from 14 to 4.7 mass ppm.

Jan 1, 2003

Since early-2001, Kalgoorlie Consolidated Gold Mines (KCGM) has successfully operated an ultra fine grinding (UFG) circuit to supplement its roaster capacity for the treatment of the refractory gold flotation concentrate. A second UFG mill was installed in 2002 taking the total UFG capacity to over 20 tph while grinding to 11 to 12 microns and achieving over 90 per cent gold recovery. A development program in 2002/3 involving plant trials, pilot plants and laboratory testwork resulted in process improvements and a better understanding of the milling and gold leach processes that assisted in narrowing the gap between UFG and roasting. This paper details the operation of the ultra fine grinding process at KCGM as a non oxidative treatment for the extraction of gold from a refractory ores.

Jan 1, 2003

"This document sets out the Exchange’s expectations and requirements for a valuation of mineral properties and outlines: the general purpose of valuation reports; guidelines respecting circumstances where the Exchange will require a valuation report; and valuation standards, guidelines and methods that are generally acceptable to the Exchange, 1. IntroductionThis Appendix sets out the Exchange's expectations and requirements for a valuation of mineral properties and outlines:(a) the general purpose of valuation reports;(b) guidelines respecting circumstances where the Exchange will require a valuation report; and(c) valuation standards, guidelines and methods that are generally acceptable to the Exchange.Mining industry standards and guidelines for valuations and valuation reports can be found in the Canadian Institute of Mining, Metallurgy and Petroleum Standards and Guidelines for Valuation of Mineral Properties (""CIMVal"") published in February, 2003 (www.cim.org). CIMVal consists of two parts, Standards and Guidelines. The Standards are mandatory and must be followed in order for a valuation to be CIMVal compliant. The Guidelines in CIMVal are not mandatory, but are strongly recommended.The Exchange requires that CIMVal Standards be used by Issuers and their professional advisors when preparing valuations and valuation reports on mineral properties. The CIMVal Guidelines should be followed by Issuers and their professional advisors in preparing valuation reports on mineral properties, with the exception that the valuation methods and guidelines under Section 4 Acceptable Valuation Methods and Guidelines below, must be followed."

Jan 1, 2003