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By M. Machikicho, N. R. Shoko, J. Chirasha

Keywords: Pyrometallurgy, furnace, ferrochromium, alloys, Zimbabwe Zimbabwe Alloys was founded in 1949 by a consortium led by the John Brown Group. It was the first ferrochrome plant in Africa. The establishment of the refinery was necessitated by an increase in world stainless steel demand and the need to reduce cost by shipping alloy rather than chrome ore. The location of the refinery in Gweru was influenced by a number of factors, not least of which were the abundance of chrome ore deposits, access to inexpensive power from Kariba, the availability of reductant coke from Hwange, accessibility to ports (as the town was well served with rail and road networks second to none in the country), and of course cheaper labour costs. The production of Low Carbon Ferrochrome (LCFeCr) was commissioned in 1953 and produced from an Open Arc Furnace with a Submerged Arc Furnace producing Ferrosilicon Chrome (FeSiCr) that is used as a reductant in the production of LCFeCr. An experimental furnace was commissioned in 1958 to help with efficiency and control on larger furnaces. A second Submerged Furnace was commissioned in 1963. Three other Submerged Arc Furnaces were built between 1967 and 1974. Several mines were acquired between 1974 and 1984, as a strategic move to ensure the growth of the refinery. A briquetting plant was commissioned in 1977, enabling the use of friable ores to enhance the capacity of ore supplies and ore cost management. A plant to recover alloy from slag was established in 1994 to capitalize on market demand without large capital outlay that would be required to build other furnaces to increase capacity. Zimbabwe Alloys has created employment opportunities throughout the years. There have been direct employment opportunities at both the refinery and the mining divisions. With time, indirect employment was realised both upstream and downstream of the refining process, enhancing the livelihood of numerous people. Zimbabwe Alloys' involvement with various labour skills has, of necessity, enabled it to develop a culture of safety at work, home, and play. Zimbabwe Alloys has contributed to society by participating and funding various local initiatives primarily to impact positively on societal needs. The latest development was in 1996, when Zimbabwe Alloys entered into a Technical Transfer Agreement with Japan Metals and Chemicals to improve the efficiencies and hence the profitability of the LCFeCr production process. A significant quantity of various alloys has been produced since inception, and significant foreign currency has been earned for the country. This was in spite of challenges that included the cyclic nature of market prices, the upheavals of sanctions affecting the macro-economic environment, and the challenges related to the deteriorating grade of chrome ore and reductant coke.

Jan 1, 2006

Development of New Comminution Testing Methodologies for Geometallurgical Mapping of Ore Hardness and Throughput The emerging discipline of 'geometallurgy' is becoming increasingly recognised as a discrete and high-value activity that reflects an ongoing trend towards more effective mine site integration and optimisation. Constrained sampling that reflects and defines inherent ore body variability is a key geometallurgical requirement. This requires use of larger numbers of low-cost physical testing which can be applied to small sample volumes suitable for defining natural variability. The AMIRA P843 'GeMIII' project (Geometallurgical Mapping and Mine Modelling) is a major industry-supported research initiative designed to develop new tools, methods and protocols to support geometallurgical integration. As part of this integrated research a new more rapid low-cost comminution test (GeM Comminution index) has been developed which can be employed as a front line tool for geometallurgical mapping purposes and predictive throughput modelling. The test has been designed to be inserted into routine assay sample preparation and is based on constrained jaw crushing protocols linked to analysis of resultant size distributions. Extensive validation and modelling has shown the GeM Comminution Index (Ci) is correlated with the Drop Weight index A*b and Bond Mill Work Index (BMWi). Large scale trials have been conducted within a commercial assay laboratory to demonstrate and optimise incorporation of the Ci test into routine sample preparation protocols. While Ci based estimates of A*b and BMWi are not as precise compared to larger volume more expensive test-work, the ability to undertake large numbers of tests typically in a systematic down-hole manner, provides a high level of data support through adjacency. A Ci based approach is highly suitable for variability mapping, domaining and selecting large composite samples for more precise testing. Within the context of the AMIRA P843 project this forms part of an integrated work flow designed to support geometallurgical integration. The development of a comminution test linked to routine assay sample preparation represents significant value adding to a process that in most cases is already going to be carried out. This paper introduces the Ci test concept and application to geometallurgical testing for throughput modelling

Sep 13, 2010

"The mining industry uses many types of mineral and metallurgical plants to produce saleable product from ore mined. Plant design history has left current operations with a mixture of manual operation and various forms of automated process controls. Consequently, we typically see high variability in the continuous operations together with a shortfall in the attainment of full capacity, or higher utilisation of consumables.At a level of best practice, ‘Operational Performance Excellence’ focuses on process control, using automation and control systems to deliver process optimisation. This more sophisticated delivery is a great deal more difficult than the first stage of equipment selection / installation. It includes the appropriate selection of the right instrumentation, control system, key process knowledge, individuals with a solid control engineering background / experience, and the essential backing / support of the operations management team together leading to higher value delivery. Robust solutions can be realised, considerably minimising process variation, thus leading to process optimisation. This approach results in an easier, efficient and safer process while providing considerable returns for the plant owners.How variable are your processes, and do you maintain optimised process performance with dedicated resources, modern instrumentation, ‘best practice’ control systems and performance monitoring tools? In this paper, these questions and their possible answers are discussed."

Jan 1, 2014

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi, Mohammad Raouf Hosseini

This study aims to investigate the effects of operational variables on concentrate grade, recovery, separation efficiency, and kinetic parameters of the copper flotation process. For this purpose, the effects of the pulp solids content, collector and frother dosage, and preparation and concentrate collection time were studied using a Taguchi experimental design. The results of statistical analyses indicated that the concentrate collection time and pulp density were the most influential parameters on concentrate grade. Considering copper recovery, concentrate collection time, collector dosage, and pulp density were the most significant variables, in decreasing order of importance. Also, the separation efficiency was mostly influenced by the concentrate collection time. Furthermore, kinetic studies showed that the second-order rectangular distribution model perfectly matched the experimental flotation data. The highest kinetic constant of 0.0756 s−1 was obtained from the test, which was performed with 35% solids content and 40 and 20 g/t collector and frother, respectively. The highest predicted copper recovery of 99.57% was obtained from the test at 30% solids content, and the collector and frother dosages of 40 and 15 g/t, respectively

By Mustapha A. Raji, Alafara A. Baba, Christianah O. Adeyemi, Aishat Y. Abdulkareem, Rafiu B. Bale, Malay K. Ghosh

The increasing demand for pure aluminum and aluminum compounds of industrial quality from kaolinite ore cannot be overemphasized. Nigeria is one of the African countries endowed with abundant solid mineral resources that have not been sufficiently exploited to assist its indigenous industries. A wide array of applications of pure aluminum and its compounds are available, such as paper filling, refractories, adsorbent, catalysis, and paint additives. In this study, the upgrading of a Nigerian biotite-rich kaolinite ore by a hydrometallurgical route was investigated in oxalic acid media. During leaching studies, the effects of parameters including reaction temperature, lixiviant concentration and particle size on the extent of ore dissolution were examined. At optimal conditions (1.0 mol/L C2H2O4, 75 °C), 92.0% of the initial 10 g/L ore was reacted within 120 min. The dissolution curves from the shrinking core model were analyzed and found to conform to the assumption of surface diffusion reaction, and the calculated activation energy of 33.2 kJ/mol supported the proposed model. The unreacted product (~8.0%) analyzed by XRD was found to contain siliceous impurities and could serve as a valuable by-product for certain industries.

By D Crequer

A Peer Review Panel for the Golden Cross Mine in the upperWaitekauri Valley, Coromandel was initiated in December 1989, before mining, as a requirement of the conditions of the Mining Licence and Water Rights. The panel's function is as a technical audit and advisory team - to provide independent technical review of design, construction, and execution of mining operations, slope remediation works, and reclamation/mine closure activities. The primary role of the panel is to act in the public interest by providing assurance to regulating authorities that the design and application of on-site mining operations accords with 'good industry practice'. Panellists are not involved in design nor as advisers, although until 1997 when explicit terms of reference were written, the panellists were a sounding board for some operational proposals. The panel functions to ensure that best mining industry technical standards are met. The costs of the peer review process are met by the mining company. Review of mining operations includes environmental matters such as land rehabilitation and water quality. The focus of this paper is on the process of peer review for environmental management factors rather than for structural and mine engineering.

Jan 1, 1998

By Mustapha A. Raji, Alafara A. Baba, Christianah O. Adeyemi, Aishat Y. Abdulkareem, Rafiu B. Bale, Malay K. Ghosh

The increasing demand for pure aluminum and aluminum compounds of industrial quality from kaolinite ore cannot be overemphasized. Nigeria is one of the African countries endowed with abundant solid mineral resources that have not been sufficiently exploited to assist its indigenous industries. A wide array of applications of pure aluminum and its compounds are available, such as paper filling, refractories, adsorbent, catalysis, and paint additives. In this study, the upgrading of a Nigerian biotite-rich kaolinite ore by a hydrometallurgical route was investigated in oxalic acid media. During leaching studies, the effects of parameters including reaction temperature, lixiviant concentration and particle size on the extent of ore dissolution were examined. At optimal conditions (1.0 mol/L C2H2O4, 75 °C), 92.0% of the initial 10 g/L ore was reacted within 120 min. The dissolution curves from the shrinking core model were analyzed and found to conform to the assumption of surface diffusion reaction, and the calculated activation energy of 33.2 kJ/mol supported the proposed model. The unreacted product (~8.0%) analyzed by XRD was found to contain siliceous impurities and could serve as a valuable by-product for certain industries.

By J. P. Powell

The importance of recovering more oil from known petroleum reserves has placed increasing emphasis on the application of secondary producing methods. One of the most successful of these has been the injection of water into depleted oil reservoirs. Water flooding is now recognized as a valuable conservation measure that not only prevents the premature abandonment of stripper leases but also is credited with reviving operations in many oil-producing areas previously abandoned. The injection of water into an oil-producing zone as a method of stimulating oil production was legalized in Kansas in 1935. Although water flooding had been attempted previously in other parts of the State, 1935 marked its introduction into the shallow stripper area of eastern Kansas. Two years later flooding was begun in the five-county area that is described in this report. Figure 1 is a map showing the water-flood areas in Allen, Bourbon, Crawford, Labette, and Neosho Counties, Kans. To July 1, 1955, the 77 projects in the oil fields of these 5 counties are credited with recovering an estimated 12.3 million barrels of oil that would not have been produced by methods used previously. These projects are expected ultimately to cover 10,700 acres, of which only 5,400 has been flooded to date.

Jan 1, 1957

The purpose of this study was to investigate the immobilization as a host for metallic pollutants (Cr, Cu, Pb, and Zn) by ettringite phase. Ettringite phase is produced through hydration reaction of calcium aluminate with gypsum. From the XRD patterns, it is known that the distance between spaces in 010 planes in ettringite crystal increase with an increase of ionic radius of heavy metal except Pb; no big difference is shown. For this reason, the d-value of 010 planes in ettringite crystal increased with the substitution of Cr, Cu and Zn having a big Al ironic radius. But in case of Pb, because the substitution occurred at calcium site, it does not influence to increase d-value of 010 planes.

Jan 1, 2006

By Steve Kral

The concept of sustainable development is not new to the mining industry. Many people involved with mining have argued that the industry throughout the world has always supported the communities where they operated. They say that the mining industry was employing sustainable development practices before the phrase became fashionable. The mines employed residents and supported the local economy through tax payments and the purchase of goods and services from local businesses. In many cases, mining companies have built medical facilities and contributed money, equipment and services to local schools. In modern times, mining companies have donated reclaimed land to the local communities for use as parks and recreational facilities.

Jan 1, 2004

By Michael G. Zabetakis

THIS is a summary of the available limit of flammability, autoignition, and burning-rate data for more than 200 combustible gases and vapors in air and other oxidants, as well as of empirical rules and graphs that can be used to predict similar data for thousands of other combustibles under a variety of environmental conditions. Specific data are presented on the paraffinic, unsaturated, aromatic, and alicyclic hydrocarbons, alcohols, ethers, aldehydes, ketones, and sulfur compounds, and an assortment of fuels, fuel blends, hydraulic fluids, engine oils, and miscellaneous combustible gases and vapors.

Jan 1, 1965

By R Moreby

This paper is a demonstration of the techniques developed during an Australian Coal Association Research Program (ACARP) funded research project aimed to develop aids, principally computer based, to assist mine personnel to more efficiently manage significant incidents in coal mines. These aids include software to aid in the location of the incident, electronic information storage and retrieval, online site emergency response manuals and software to aid in decision-making.

Jan 1, 2005

By Donald Leroux, Ralph Dahlke, Dave Scott, Finch. James A., Cesar O. Gomez

"The efficiency of the flotation process depends on how effectively air is dispersed into small bubbles. Bubble surface area flux - the surface area of bubbles per unit time per unit cross-section area of a cell - is emerging as the parameter to characterize gas dispersion. One of the approaches proposed to measure bubble surface area flux in industrial cells is based on the measurement of two variables: gas velocity and gas holdup, using separate sensors. Plant testing of the gas velocity sensor gave evidence of a series of operational problems which may be necessary to correct before attempting to characterize gas dispersion. Problems such as uneven air distribution within a cell and along a bank, faulty air and slurry valves detected during attempts to redistribute air, and poor control of pulp level and gas flow became evident. Detection of these problems from gas velocity measurements is illustrated.INTRODUCTIONBubble surface area flux is considered a key variable in the optimization of flotation circuit performance (Gorain et al., 1997; 1998). The Mineral Processing Group at McGill University has devised and developed a method for estimating bubble surface area flux in industrial flotation cells (Finch et al., 1999). The method is based on measuring gas holdup and superficial gas velocity using two separate sensors and applying drift flux analysis to estimate bubble size (Dobby et al., 1988; Banisi and Finch, 1994). With bubble size and superficial gas velocity known bubble surface area flux can be calculated.This method was selected by Noranda to characterize gas dispersion in cells as part of a program to model and optimize flotation circuit performance. However, initial testing at Brunswick Mine with the gas velocity sensor provided some unexpected results indicating operational problems and equipment malfunctions that needed to be addressed before systematic measurement of gas dispersion could be initiated.The subject of this communication is to illustrate the detection of these problems from gas velocity measurements. The line 3 Zn Cleaner circuit comprising four stages of Denver DR cells was the main subject of analysis, including the effect of correcting these problems on the metallurgical performance of the Zn 3rd cleaner bank of ten DRl 00 cells."

Jan 1, 2001

By Michael Young, Josh Rubenstein, Michael Cooper, Tom Shouldice, Dan Curry

"Xstrata Nickel Australasia’s Cosmos plant in Western Australia is currently implementing a debottlenecking project to increase nickel output while maintaining metallurgical performance and a low unit cost for production. Mineralogical analyses indicated that the processing bottlenecks could be removed by simply reconfiguring portions of the circuit as well as adding capacity with technical advancements – notably an IsaMill™, Jameson Cell, Wemco® SmartCell™ and Larox Filter.The Wemco® SmartCell™, which is particularly suited for coarse mineral flotation, and Jameson Cell, which is particularly well suited for fast floating and fine minerals, combine as rougher scalpers to complete the main stream portion of the flotation circuit. Addition of the two new cells meet the required flotation capacity to handle the forecast increase in nickel feed grade and tonnage.The addition of an IsaMill™ for regrinding allows the SAG mill to produce a coarser primary product, thus enabling increased throughput. The advantages offered by the IsaMill™ include operation in open circuit (internal classification), an inert grinding environment (ceramic media) for better downstream flotation (“clean” new surfaces), compact footprint (easy to retrofit into existing plant) and energy efficiency. With the new rougher capacity addition, the remaining original plant cells were reconfigured to suit the new regrind mill and cleaning requirements. The existing 24 m2 Larox pressure filter was replaced with a larger 32 m2 unit to dewater the increased concentrate output.The paper describes the upgrade at the Cosmos concentrator with particular emphasis on the mineralogical data and metallurgical benefits associated with the changes.INTRODUCTIONThe Cosmos concentrator is located 680 km northeast of Perth in Western Australia. The deposit’s development and operations were started in 1999 by Jubilee Mines NL, Cosmos’ previous owner, with the first production of nickel concentrate in April 2000. The Cosmos concentrator treats a komatiite hosted high grade nickel sulphide ore, with sulphides being predominantly pentlandite and pyrrhotite with lesser amounts of pyrite and chalcopyrite."

Jan 1, 2010

By P Williams, S Flynn, R Birchfield, R Simcock, R Toft, P Comeskey

Direct transfer, or community translocation, comprises salvage and replacement of intact æsodsÆ of vegetation together with underlying soil. It has been applied to New Zealand mine sites restoration of native grasslands, wetlands, scrub lands, and forest. It is an equivalent technique to æinstant lawn or tree gardenÆ, commonly used in urban landscaping. Two to six m2 scoops of vegetation, with up to 0.7 m of soil attached, and including root plates of trees and shrubs, are relocated from stripped areas ahead of mining to sites prepared for restoration. Direct transfer uses hydraulic excavators or face shovels and dump trucks, possibly with the aid of bulldozers and other earthmoving machinery. The main advantages of direct transfer, compared with sowing or planting systems for mine site restoration, are the recycling of plant and soil materials which were often wasted by burying under overburden materials, a significantly faster revegetation process, and restoration of the whole ecosystem (plants, animals, birds, invertebrates, and microbes). The main disadvantages are higher costs of stripping and dumping, a greater degree of machine operator skill required, and scheduling becomes critically important. To illustrate the key principles, this paper gives examples of successes and failures of the technique for a variety of New Zealand mining situations. Direct transfer has been successful for a range of communities, from fern wetland and sub-alpine tussock grasslands to 5 m-tall beech forest under storey and seral shrub land, and from temperate to sub-alpine climates. Successful examples show both rapid recovery of indigenous vegetative cover and conservation of habitat for birds and invertebrates. Failures have resulted from excessive death of plants because of inadequate soil salvage depths, acidic leachates, inappropriate handling of stripped sods by inexperienced machinery operators, or prolonged drought conditions immediately following relocation. Change in plant species composition has occurred where clumps of vegetation are too far apart, or shifted plants were too small - in both cases invasive weeds have smothered the original vegetation. Changes in hydrology can also have significant impacts. Our experience indicates that the advantages of direct transfer far outweigh the disadvantages and is now used as the preferred restoration method, where practicable, at mines where it has been trialled.

Jan 1, 2000

By R. J. Hundermark, L. R. Nelson

The critical importance of tap-hole design and management to furnace performance and longevity is explored through examining some of the specific matte, metal and slag tapping requirements of non-ferrous copper blister and matte converting and smelting, ferroalloys smelting and ironmaking systems. Process conditions and productivity requirements and their influence on tapping are reviewed for these different pyrometallurgical systems. Some critical aspects of the evolution of tap-hole design to meet the diverging process and tapping duties are examined. Differences and similarities in tapping practices and tap-hole management are reviewed. Finally core aspects of tap-hole equipment and maintenance are identified that are considered important to securing improved tap-hole performance and life, so pivotal to superior furnace smelting performance.

Jan 1, 2014

By Bruno KERL

THE list of deaths reported during the year 1905 comprises the following names (the figures in parentheses indicating the year in which the persons named were elected to membership:- Honorary Member.-Dr. Bruno Kerl. Members and Associates.-Charles Christy Adams (1903), John Wesley Anderson (1898), William Burton Barber (1901), Thomas A. Bennett (1900), Luke W. Bryan (1901), Edwin S. Daugherty (1905), William Scott de Camp (1875), George H. Eldridge (1889), B. W. Frazier (1871), John Broome Guinn, Jr. (1897), Dana C. Irish (1900), Harry Hugh Lee (1899), William Alfred Lindsay (1902), Roland C. Luther (1884), James MacNaughton (1890), Gordon McLean (1899), Herbert Holmes McNamara (1902), August R. Meyer (1886), William Orr (1897), William J. Parker, Jr. (1898), Joseph Phillips, Jr. (1895), Charles O. Ripley (1902), Emmerich J. Schmitz (1883), Ludwig Philip Seeger (1900), Jacob Johnston Sperry (1900), Gustavus H. Stoiber (1902), William L. Study (1905), Robert Macnair Wilson Swan (1900), Richard Henry Terhune (1886), Joseph Thiry (1892), John N. Tisdale (1903), Alfred Isham Totten (1897), Walter H. Virgoe (1902), Charles H. Wellman (1890), Harvey L. Williams (1903). Of these, Dr. Bruno Kerl and Prof. B. W. Frazier have been made the subjects of special Biographical Notices in the Bi-Monthly Bulletin 1 the former in No. 4, July, 1905, p. 743, and the latter in No. 5, September, 1905, p. 1097. Concerning the remainder of the list, the following paragraphs comprise such information as could be obtained by the Secretary. Charles Christy Adams, who had been a member of the Institute since 1903, died in Johannesburg, South Africa, August 31. 1905. He was born in New York City, July 13, 1849, and received his technical training at the Colorado State School of

May 1, 1906

These proceedings consist of papers presented at two Bureau of Mines Technology Transfer Seminars in early 1980 for the purpose of disseminating recent advances in mining technology related to surface coal mining reclamation.

Jan 1, 1980

By Met M. E, Worner H. K

During the past two years, a large number of creep tests has been carried out on electrolytic lead, special assay lead and ordinary refined (Port Pirie) lead. Some of these tests have already been reported.1§ In addition, an attempt has been made to estimate the influence of the individual elements present in small traces in Port Pirie lead. The present paper gives the results obtained when small additions are made to "U" lead of the composition shown in Table 1.(which has been used throughout these investigations during the past few years). The additions were silver, antimony, bismuth and zinc. The results of the addition of tellurium have already been communicated. This investigation was intended to run parallel with a similar one using electrolytic lead as a basis and adding one element at a time.Actually, the experiments using "U" lead have got rather ahead of the others. The important point has emerged, however, that the effect of a .given addition may be appreciably influenced by the presence of traces of other elements.In most of these tests, an initial stress of 500lb. per sq. in. has been used. Whilst it is fully appreciated that this stress is higher than those used in practice, it has to be borne in mind that an improvement in creep resistance was *Manuscript received December 11th, 1936.

Jan 1, 1936

By William O. Vanderburg

This report3/ gives the results of a reconnaissance of mining districts in Eureka County, Nevada, made from September 25 to October 20 and from October 27 to November 5, 1577. During this time, virtually all the districts were visited and many data obtained on active and inactive properties. This report covers the locations of the various districts, geological background, ownership and brief descriptions of mines and prospects, information on past and current operations, and, other data likely to be useful to those interested in the development of our mineral resources. From the viewpoint of past production in the county, the silver-lead-gold deposits at Eureka have been tie most important, followed by the silver deposits at Cortez and Mineral Hill. The period of greatest activity in the foregoing districts was from 1870 to 1990, when Eureka was one of the principal mining areas in Nevada; the production of lead was sufficient to affect its price in all the commercial centers of the world. Eureka also merits the distinction of being the birthplace of the silver-lead smelting industry in the United States.

Jan 1, 1938