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By Hemraj Dangi, S. Murali, Bhisham Yadav, Mohini Saxena, P. Asokan

"Demonstration studies were carried on the use of fly ash as soil modifier and supplier of micronutrients to improve the agricultural productivity based on the process optimised at lab scale at Advanced Materials & Processes Research Institute, Bhopal. The field trials were conducted in Uttar Pradesh (North India) Orissa (South Eastern India) and Madhya Pradesh (Central India) under different soil and crop conditions. 100-650 tonnes of fly ash per hectare were applied depending upon the soil and fly ash characteristics. Both short and long term studies on impact of fly ash on soil and food quality were conducted. With the fly ash application, the edible yield of tomato, cabbage, potato, wheat, pea, onion, paddy, sunflower, maize etc., were increased from 12 - 46% as compared to the control soil where no fly ash was used. The crop response to various elements mainly heavy metals grown in soil and fly ash applied soil was found comparable to that of control, which are within the permissible limits and meet the food quality standards. The results of impact of fly ash on biotic and abiotic properties of soil, along with the quantity and quality of agricultural produces generated under pilot scale demonstrations in three different parts of India are discussed in this paper. The outcome of this work could act as guiding force for confidence building and to maximise the use of fly ash, generated from thermal power plants worldwide as one of the major mineral waste for agriculture purposes.IntroductionThe advantages of application of fly ash in terms of improvement of soil properties and crop yields have been published by various researchers in India and abroad. Attention is also given about the possible negative and beneficial impact of pond ash in agriculture due to presence of heavy elements, radioactive nuclides and plant nutrients in fly ash. It is evident from the analysis of Indian fly ash that the presence of heavy elements and radionuclides levels are comparable with normal soil. The positive impact that has been reported is with regard to germination, yield and crop growth. The significant impacts are: long term effect of heavy and toxic elements content of fly ash on soil and up take of these elements by plant. Pilot scale demonstration studies have been completed with varying soil crop-combination under different agro-climatic conditions showed considerable improvement in the productivity of cereals, oil seeds and vegetables."

Jan 1, 2008

By B. S. Terry

Experiments have been conducted to assess the feasibility of capturing bearing emissions arsenic with CaO during the roasting of enargite (Cu3AsS4). Enargite/CaO mixtures have been heat treated in air, nitrogen or oxygen for various times and the products of reaction analysed by X-ray diffraction and cleaned analysis. The results show that substantial capture of arsenic can be achieved via the formation of calcium arsenates and/or calcium arsenides. In addition significant capture of sulphur is achieved by the formation of calcium sulphate andlor sulphide. Complete conversion to copper sulphide with total removal of arsenic can be achieved within 30 minutes at 700°C. Further heat treatment in air or oxygen leads to the formation of copper oxide and copper oxysulphate. Without optimisation of reaction conditions, it has proved possible to achieve retention of in excess of 85% of the arsenic content of enargite in the form of calcium arsenates.

Jan 1, 1994

By Willy Persson

A common feature of the kinds and amounts of impurities present most pyrometallurgical, processes is injection of oxygen to, remove various in the feed. The degree of success of a specific process step relies critically on control of the instantaneous oxygen potential/oxidation stage, throughout the step as well as upon termination of the step. This will, for instance, determine the distribution of impurities between metal and slag. As long as the operation is perturbation free -detailed analysis of all additions and application of advanced models often yield satisfactory control means However, a pyrometallurgical process is seldom free from disturbances, which reduces the accuracy of the static models and leads to inconsistencies in scheduled route might be uncontrollable changes in quality and quantity of feed, operator interventions and shift changes, timing of cranes, lining wear and accretions etc. The implementation of dynamic, control to correct for disturbances and, more generally for process optimization, requires continuous on-line information on, the actual status of the process. The implementation of sensors for continuous process monitoring, e.g., as regards the instantaneously prevailing oxygen potential or oxidation stage, has been hampered by the highly aggressive environment in smelters; This is. where remote-sensing techniques based on optics and spectroscopy, have proven to form invaluable, tools towards the realization of dynamic production control. Since about 15 years Semtch has developed and industrialized a remote-sensing technology, based on ,optics and spectroscopy, for continuous on-line process monitoring and production control of various pyrometallurgical processes. The presentation will discuss applicability aspects with examples and experiences from installations and tests in ferrous and non-ferrous industry. Keywords: Applied spectroscopy, Metallurgy, Process monitoring, Production. Control

Jan 1, 2003

By T. T. Chen

This mineralogical study is based on samples from typical "wet" nickel laterites of humid tropical to sub-tropical regions. An in-situ nickel laterite sample from Goro and a transported laterite sample from Plaine des Lacs, New Caledonia, are predominantly limonitic. Two-thirds of the particles in the Goro sample are <10 um in size; they consist of skeletal goethite and serpentine, as well as minor amounts of talc, gibbsite, chlorite, quartz and clay minerals. The coarser grains are mainly Cr-spinel, serpentine, gibbsite and Mn oxide. Nickel occurs mainly in goethite, serpentine and Mn oxide; cobalt occurs in goethite and Mn oxide. The Plaine des Lacs sample is finer-grained and contains more Al and CO3, but less Mg and Si than the Goro material. The sample contains more kaolinite, chlorite, siderite and feldspar, but less serpentine and gibbsite than the Goro material. Nickel is detected mainly in goethite, serpentine, Fe-Mg silicate and Fe-Mn oxide. The Indonesian ore from Sorowako, as sampled from the reduction kiln feed containing some reverts, is predominantly saprolitic, with apparent particle sizes ranging from <100 um to > 1 cm. The sample of reduction kiln feed is rich in Mg silicates, Mg-Fe silicates and goethite, and exhibits complex alteration textures. The nickel contents vary from particle to particle. Nickel is present mainly in serpentine, olivine, chlorite and amphibole, and in subordinate amounts in goethite and Mn oxide. Cobalt is detected in the Mn oxide. Keywords: Nickel Laterite; Mineralogy; Nickel Carriers; Goro, New Caledonia; Plaine des Lacs, New Caledonia; PT Inco., Sorowaki, Indonesia

Jan 1, 2004

By Robert D. Pehlke

"Current continuous casting processes are going through a rapid evolution of advances and new developments. At the same time, intense efforts are being directed to the development of radical new technologies such as continuous casting of thin slabs and strip steel.Traditionally, the casting processes for steel have been anticipated by the development and implementation of processes in the non-ferrous industry. This trend is reviewed and what it may portend for steel is described.IntroductionThe continuous casting of steel has been a widely adopted process in the production of steel. The concepts for this processing go back into the early and mid 1800's; however, commerical development was delayed for a variety of reasons until the mid twentieth century.Beginning in the early 1960's, adoption of continuous casting was initiated and continues at this point in time to be accelerated. In Japan, more than 90% of the steel produced is continuously cast (1). More than 50% of the steel produced in the United States is continuously cast and this fraction continues to rise (2). Numerous examples can be cited of installations costing well over $200,000,000 which have provided a payoff in less than a year and a half. As this process has continued to be applied and its technology to increase, computer control systems have been installed. In particular, in the larger plants producing slabs, sophisticated computer systems involving the integration and networking of mini-computers, micro-computers, and mainframe including back-up systems at all levels are being utilized. Pehlke (3), and Harabuchi and Pehlke (4) have described the structure of these systems."

Jan 1, 1988

By J. F. White

An experimental study was undertaken to evaluate the feasibility of a selective chloridizing roasting pre?treatment process for the elimination of impurities from zinc feed?stocks prior to recovering zinc by conventional unit operations. In this investigation, a number of chemistries that might serve as a basis for such a pre? treatment process were examined. A variety of chloridizing agents were admixed with EAF dust to promote the selective removal of lead and cadmium by the formation of volatile metal chlorides, he results of the experimentation firmly establish that selective chloridizing roasting is a technically feasible means of eliminating lead and cadmium from EAF dust. Excellent extraction efficiencies were accomplished with a number of chloride additives; as high as 98 percent lead extraction and 88 percent cadmium extraction were attained with minimal zinc losses, Continuous pilot?scale tests reinforced the trends established by laboratory?scale experimentation, Attempts of chlorine elimination using pyrohydrolysis were less successful. The extent of chlorine elimination was found to be highly dependent upon EAF dust sample type and treatment temperature.

Jan 1, 1996

By Guan-Yong SHI, Cong Wang, Zhi-he DOU, Ting-an ZHANG, Shi-gang FAN

Based on the pre-works, this paper proposed a new short stage process of the intensify aluminothermy reduction by the stage to prepare high titanium ferroalloy with low O and Al contents. We investigated the effects of Al and Ca and Si combination reduction agent, slag type and step-up reduction conditions on the Al content and distribution in the alloy. The results show that the step-up reduction can not only reduce effectively the oxygen content in the alloy, but also reduce effectively Al content. For instance, the oxygen content in high titanium ferroalloy is within 1%~4%, and the Al content is within 1%~5%. Its quality reaches the requirement of high titanium ferroalloy prepared by remelting process.

Jan 1, 2015

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist&apos;s tools.

Jan 1, 1981

By Hideharu Fukunaga, Jin Pan

"The recognition of Metal Matrix Composites (MMCs) as a means of providing high specific strength, high specific stiffness, excellent wear resistance, low thermal expansion and improved high temperature properties has led to a number of new processing, not previously used for plastic and ceramic matrix composites. As a primary fabricating process, the liquid methods are the major ones, which are reviewed briefly from the view of processing terminology. One of them, squeeze casting process is the most traditional and well-developed, because it is rapid, versatile and near-net shape production of materials. Two of new squeeze casting processes are presented to offer the hardness· controlled MMC and the· functionally graded MMCs as well as a newly developed whisker preform.I .IntroductionA large number of liquid processes and techniques including semi-solid liquid process are proposed. The most primitive process is ''pressure infiltration casting” of liquid metal into the fiber preform. It is called as follows depending on pressure and its source squeeze casting (1-4) by hydraulic ram, gas pressure infiltration casting (5, 6), vacuum infiltration, centrifugal casting (7), Lorentz-force-driven infiltration (8). The pressurizing on the liquid metal requests a large and stiff equipment, so pressureless infiltration technique has been developed using K2ZrF6 flux (9,10) while the mechanical properties are not high enough, and using H2 gas with Mg alloying element called pressureless infiltration casting (11-13), spontaneous infiltration process (14) and PRIMEX (15). In those processes, no severe reaction occurred between the reinforcement and matrix molten metal. In early l 990's, the reactive processing with pressure or without pressure, in which one material is totally transformed into another of the required shape, eq. assisted oxidation, has been developed, called reaction squeeze casting (16,17), DIMOX (18) reactive infiltration casting (19,20), and in-situ process (21,22). Die casting of SiCp/Al alloy (23,24) and thixocasting of SiCp/Mg alloy (25) are also applied to produce the machine component of MMCs."

Jan 1, 2000

By Hiroyuki Sano, Chikabumi Yamauchi, Mitsuru Tanahashi, Toshiharu Fujisawa, Shin-ya Iwahori

"Pyrometallurgical process using Cu2O-based slag was proposed as a recycling process for copper scrap. However, it is difficult to remove nickel from copper by oxidative refining. Therefore, it is necessary to reduce the concentration of nickel in copper before the oxidative refining. In the present work, the copper enrichment stage in this recycling process, where copper scrap melt is separated into the Fe-C-Cu melt and the molten copper, was taken up and the compositions of both melts were measured. Based on the above results, the distribution ratios of nickel between the Fe-C-Cu melt and the molten copper were calculated. Furthermore, the optimum condition of copper enrichment stage was discussed from the viewpoint of nickel removal and copper recovery. The possibility of recovering 4N-purity copper by using this recycling process was confirmed.IntroductionRecycling is well known as a method for saving resources and reducing environmental damage. More than 99% of copper is used in metallic form - as metal or copper alloys[l]. High-grade copper scrap is directly re-melted and reused, while low-grade copper scrap is transported to copper smelters to be pyrorefined and electrorefined. Nevertheless, a great amount of copper is being stockpiled in the cities and should be recycled in the near future. At that time, the current recycling process will face new problems due to the increases in the recycling rate to the smelters. This includes insufficient combustion heat to melt copper scrap and ·almost no benefit in electrorefining because the scrap does not contain gold and silver. Thus, an alternative pyrometallurgical method for copper scrap refining will be required."

Jan 1, 2000

By T. K. Bundtzen

Placer gold in the Iditarod and Innoko mining camps of western Alaska is derived from a suite of comagmatic, Late Cretaceous to Early Tertiary, alkali-calcic, meta-aluminous. volcanic-plutonic complexes and peralumi-nous rhyolite sills that intrude Mesozoic flysch. Heavy-mineral concentrates from 42 mining operations and streams draining known mineralized areas in the igneous complexes contain placer gold and a variety of ore minerals derived from epithermal to hypothermal conditions of formation. The minerals include cassiterite, ilmenorutile, samarskite, cinnabar, scheelite, chromite, stibnite, silver sulfosalts, monazite, and zircon. Results of the study show that 1) cinnabar. stibnite, and quartz formed with the bulk of the placer gold in an epithermal lode environment, 2) chromite appears to have originated in mafic phases of monzonite plutons and alkalic basalts, and 3) niobium-tin-tungsten-uranium-silver values may have been derived from stockwork accumulations in cupolas of monzonite plutons.

Jan 1, 1987

By David R. Jessey

An ore microscopic and geochemical study of the nickel-cobalt occurrence in the Southeast Missouri Mining District has revealed several significant relationships. Siegenite [(Ni,Co)3S4] is the dominant nickel-cobalt sulfide in the ores, however, several other members of the thiospi¬nel group (AB2S4) occur: carrollite (CuCo2S4), nickelean carrollite [(Co,Ni,Cu)3S4], fletcherite [Cu(Ni,Co)2S4] and polydymite (Ni 3S4). In addition, bravoite [(Ni,Fe)S2], vaesite (NiS2), millerite (NiS) and gersdorffite (NiAsS) are present. Thiospinel composition varies dramatically within the district. Paragenetic studies have shown that the stratigraphically lowest thiospinels are the most cobalt-copper-rich. A detailed ore microscopic study of the AMAX Lead Company Buick mine has also shown significant changes in mineralogical association, texture and grain size of the siegenite along the north-south strike of the major ore bodies. Siegenite commonly replaces and veins chalcopyrite and is subsequently replaced by sphalerite. Less commonly, siegenite and chalcopyrite are observed to form linear replacements along sphalerite grain boundaries. The grain size of the siegenite varies markedly, but in a predictable north-south pattern that is consistent with a genetic model formulated from geo-chemical data. The compositional as well as textural trends displayed by the thiospinel mineralization could be exploited to optimize recovery of any or all thiospinels of economic interest.

Jan 1, 1981

By Sang Han Son

The vapor pressures of FeCI2 and ZnC12 in the FeCl2-ZnCl2 system were measured by the transpiration method at 873K and 917K. The vapor pressure data were interpreted to indicate the formation of complex ions in the FeCl2-ZnCl2 melts. It is presumed that the complex molecule FeZnCl4 as well as FeCI2 and ZnCI2 exists in the vapors in equilibrium with molten FeCl2-ZnCl2 mixtures. The activities in the FeCl2-ZnCI2 system are shown a negative deviation from Raoult&apos;s law. These results suggest the formation of complex ions such as ZnCl42- in molten FeCI2-ZnCI2 mixtures.

Jan 1, 2003

By O. Norman Lotter

There are many scales of innovation in the pursuit of concentrator performance improvement, including paradigm change, inventive change and incremental change. All are important, but the last is low risk, low cost and has a relatively high probability of success, given the right metallurgical skills. Seeking continuous improvement is also essential to ensure that performance does not decline over time due to ore type changes, personnel changes, equipment wear and other factors. When properly implemented, these small gains offer a very high rate of return for the project cost because they are made from marginal, not total, operating costs of the plant. To be effective this approach requires plant trials that use designed structure and appropriate statistics to test the observed differences arising from the old and new process treatments, be they a change in flotation reagent, in grind, pulp density, etc. However the pursuit of small but financially significant performance gains is often regarded as fruitless because of the range of variance in plant data, and the consequent difficulty of ‘proving’ that a benefit has been achieved. Opportunity for improvement is thus sometimes relegated to the realm of the impossible, or at best, treated with skepticism. Operations managers prefer to look for the larger gains, which are easier to demonstrate and prove. Unfortunately, these are seldom to be found; rather, a large gain can be more easily made by executing a series of small recovery improvements that are together equivalent to the ephemeral single large gain. In this paper we advocate a policy of continuing improvement driven by rigorous performance testing protocols and a formal ‘risk analysis’ approach to judging the efficacy of changes implemented in the plant. Following these simple procedures allows rational decisions to be made on the basis of quantifying risk and reward. In particular we consider the choice of hurdle rate for decision-making which best balances risk and reward. It is shown through case studies from actual industrial practice that this approach is practical and delivers significant financial value to the operation.

By Allan MacRae

Freeport-McMoRan Inc. operates an ISASMELTTM furnace for the smelting of copper concentrate at the Miami Smelter in Claypool, Arizona. In May 2017, the furnace was restarted after incorporating newly designed copper cooling elements from just above the tap hole to the underside of the roof. The objective of the improved cooling design was to extend campaign life by eliminating existing failure mechanisms with the wall refractory. In addition to upgraded bathline coolers and complete coverage of the gas offtake transition, or ‘kettle’, with plate coolers, a novel arrangement of coolers was installed in the remaining freeboard area. The shell required significant cutting and re-stiffening, as well as extensive modification of the cooling water piping. Based on performance observed to date, it is expected that smelter throughput will be increased due to extended ISASMELTTM refractory campaign life.

By Sang Han Son

The vapor pressures of FeCL2 and ZnCL2 in the FeCL2?ZnCL2 system were measured by the transpiration method at 873K and 9I7K, The vapor pressure data were interpreted to indicate the formation of complex ions in the FeCL2?ZnCL2 melts, It is presumed that the complex molecule FeZnCl4 as well as FeCL2 and ZnCL2 exists in the vapors in equilibrium with molten FeCL2-ZnCL2 mixtures, The activities in the FeCL2-ZnCL2 system are shown a negative deviation from Raoult&apos;s law. These results suggest the formation of complex ions such as ZnCL14 in molten FeCI2?ZnCL2 mixtures.

Jan 1, 2003

By T. Nagano

Mitsubishi Metal Corporation started the development work of a new process for continuous production of copper in 1961. After a series of experimental and semi-commercial operations, the first commercial plant of the Mitsubishi Continuous Copper Smelting and Converting Process was put into operation in March, 1974. The new plant, which has a design capacity of 4,000 metric ton copper per month, was built within the premises of Naoshima Smelter, replacing the old No.1 reverberatory smelter there. The SO2-rich exhaust gas from this new plant is blended with the off-gas of the No.2 reverberatory furnace for production of sulfuric acid and the overall emission of sulfur at Naoshima has been greatly reduced. The operation of the continuous plant has been satisfactory and several advantageous features of the Mitsubishi Process have been proven on a commercial scale. This paper first gives a brief description of the history of the development work and the characteristic features of the process. The paper then describes the new commercial plant and operating data obtained so far.

Jan 1, 1976

By John J. Mortvedt

Application of some by-products of the metals industry which contain plant nutrients to agricultural lands could constitute resource recovery instead of costly disposal. Some industrial by-products contain appreciable concentrations of heavy metal contaminants, such as Cd, Cr, Ni, and Pb. After land application, these metals may be absorbed by plants and enter the human food chain or be leached to groundwaters. Plant uptake of these heavy metals varies with plant species:, soil pH, soil texture, and the particular metal. Certain leafy vegetables can absorb significant amounts of heavy metals, while absorbed metals are usually poorly translocated to cereal grains. Allowable heavy metal concentrations in fertilizers now are not regulated, but EPA is considering such regulations. Heavy metal impurities in animal feed supplements are regulated by the states; so some by-products may not be permitted for this use.

Jan 1, 1992

By D. M. Hausen

The term "auriferous pyrite" relates to an association of gold with pyrite in a variety of textural forms that affect metallurgical treatment. Extraction of the gold depends not only on the grain size and distribution of the gold in the pyrite, but also on the crystal size and surface area of the pyrite. Occlusions of medium to coarse gold may be liberated by moderately fine grinding. The amenability of finely dispersed (submicroscopic) gold depends in part on the activity of the pyrite surface for oxidation. Two types of auriferous pyrite at Carlin, Nevada, have been examined by optical microscopy and SEM methods before and after aqueous oxidation test work to show how differences in morphological features can affect rates of oxidation and amenability to gold extractions by methods of chlorination and low temperature oxidation.

Jan 1, 1981

By Alberto Oalvez, Lucya Yunus, Pengfii Tan

"Laboratory flotation tests of slow cooled converter slag have showed that 92.5% copper recovery at the copper cut-off grade of 24 - 25 % can be achieved by using a 50:50 ratio of DSP330 and SIBX (sodium isobutyl xanthate) at the natural pH of 7 and with a grinding time of 18.5 minutes. 70ìéç is the P80 achieved at this grinding time. MIBC is the frother and the solid content of the flotation feed was 46%. In the plant trials, two types of collectors at two different feed particle sizes for both the normal and slow cooled slag were operated. The particle size was controlled by the feed rate. The P80 of 75 ìçé at a feed rate between 32 - 36 t/h were tested. The plant trials have demonstrated that the copper recovery in the milling and flotation process of the slow cooled slags was improved by 3%. IntroductionIt is proposed to float the slow cooled converter slag, in the auxiliary circuit of the copper concentrator at Mount Isa, by using the processing conditions identified from several laboratory flotation tests. Among these laboratory tests, one produced a copper recovery of 4 % higher than those achieved from a normal cooled slag with the same slag feed grade and the same copper content (24 - 26 %) in the concentrate. These test conditions were selected for further studies.Laboratory Test Work and Plant TrialsThere has been a lot of work conducted under laboratory and plant conditions [1]. However, the achieved results did not justify their total implementation in the Mount Isa Copper Concentrator. Initially, the lab trials were carried out with slag cooled 100% in air; then it was changed to combined cooling for 12 h with air and 2.5 days with water sprays. The reason for this change was the shortage of space when the slag was cooled 100% in air, as it takes several days to achieve safe temperatures for its removal. The San Manuel Copper Smelter has reported that their slag was left for air cooling in pits for 8 h and then was followed by water cooling for 2-3 days [2]"

Jan 1, 2012