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By M. J. Bunyard, I. Mullany

"The pressures on mine operators are varied and constantly increasing, declining ore grades, more remote locations and increasing environmental concerns. The challenge facing the mining industry is to find new ways to process ores which are more efficient and less costly and to control them better. This requires a fundamental rethink in the way in which projects are developed, it is no longer good enough to just copy what has been done before. The process starts with the surfacing of the primary underlying constraints for the project and the establishment of new design principles to address these. The generation of new design criteria and processing options follows the well-established path of brainstorm, focus, brainstorm, refocus and economic evaluation. The aim is process intensification, doing more with less, as early as possible and better use of plant data. The methodology requires a complete geometallurgical understanding of the orebody to facilitate the evaluation of viable processing options. Examples of early stage processing considered are blast optimization and ore sorting to reject waste and reduce processing costs. Mine to mill integration, which starts with the optimization of blasting for separation, offers another way to significantly reduce operating costs and increase efficiencies.VALUE MODEL The mining industry has, over the past decade, experienced an unprecedented cycle of increased commodity prices and investments in new mining and processing capacity followed by a market collapse and fall in prices and confidence. Whilst there are now some signs of a return to investment in new capacity, the metals and mining industry is still wrestling with eroding margins and investor demand that companies achieve the full value of their assets. Metals and mining companies must work on all available levers to deflate their costs back to more manageable levels and capture the full value for their products. Levers include optimizing external spending, re-thinking make vs buy trade-offs, debottlenecking, improving availability and operating time of key equipment, more accurate and agile planning processes, value-in-use optimization, and tighter performance management. Figure 1 is a diagrammatic representation of a company’s value model. The three goals of a successful mining enterprise are social acceptance, environmental acceptance and sound financial returns to shareholders. Some of the KPI’s used to measure the success or not of achieving these goals are shown in the translation layer."

Jan 1, 2017

By Hong Yong Sohn

A novel flash ironmaking technology is under development at the University of Utah under the support of U.S. Department of Energy (DOE) and American Iron and Steel Institute (AISI). The history of the development from the conception of the idea to the current status will be discussed. The flash ironmaking process produces iron directly from fine iron ore concentrates without requiring cokemaking and pelletization/sintering, which will enable the technology to significantly reduce energy consumption and carbon dioxide emissions compared with blast furnace ironmaking. Unlike other gas-based ironmaking processes, this technology will not suffer from the problems of solid sticking and fusion. Current work is focused on the method of supplying the energy required to maintain the necessary temperature, as an intermediate step to determine the scalability for larger, industrial-scale pilot trials.

Jan 1, 2014

By Gale L. Hubred

Kennecott?s Ledgemont Laboratory developed the Cuprion Process to recover metal values from manganese nodules in the early 1970s. A reducing leach of monovalent cuprous ion attacks the manganese oxide matrix, converting the manganese dioxide to manganese carbonate and releasing the copper, nickel, cobalt, and zinc as ammine complexes. Cuprous ion is generated by contacting leach liquor with carbon monoxide. Copper, and nickel, are recovered by solvent extraction and electrowinning. Cobalt is precipitated as cobalt sulfide and recovered as cobalt powder. Manganese, molybdenum, and zinc can be recovered optionally but have not been included in this process. Kennecott authors have described aspects of the process, but the Cuprion process has not been revealed except in patents. Tables are included for capital and operating costs and revenue. Even though economic recovery of nodules is not anticipated in the foreseeable future, some of the process steps may have application in other places. The Ledgemont Laboratory was a unique operation we think worth documenting. The report is based upon work done up until the mid 1970s. The report represents the work of the entire Kennecott nodule team. It is this author?s intention to save this result and credit the work of that nodule team. The paper is dedicated to the memory of Dr. Herbert Barner, a key member of the team who died in 2003.

Jan 1, 2005

By A Price, D Okle, K Brooks

The operation of flotation plants has been improved over the years by use of fundamentally based design techniques, a better understanding of reagent chemistry, online metal analysis and the use of digital control systems. However, optimal operation of flotation banks is not consistently achieved using manual operation. The reason for this is that the system is a highly interacting one, with changes in air addition, cell interface level and reagent dosages all being available, without it necessarily being clear as to which change should be made for a particular situation.This situation is made more complex by the fact that the feed to a flotation bank can vary in flowrate, composition and density over a fairly short period of time. It is not possible for a human operator to reject these disturbances, given the extent of the operation that is typically being monitored.Model predictive control (MPC) is a control and optimisation technique, developed in the oil refining industry, that aims to manage just such interacting multiple input multiple output (MIMO) systems. This technology makes use of linear dynamic models of the plant, that are experimentally derived. These models are then used in a receding horizon strategy to determine an optimal trajectory of the inputs to the system.MPC has been applied to four areas of the lead zinc flotation unit at Mount Isa mines. A total of 31 cells are being controlled by the system, which varies air to the cells, levels and reagent addition on a minute-by minute basis. The MPC controls concentrate and tail grades, reagent dosages, as well as recoveries to ranges set by the plant metallurgists.The development of the MPCs is discussed, together with the benefits realised. The key factors in insuring an ongoing return on investment are described.CITATION:Price, A, Okle, D and Brooks, K, 2018. Glencore Mount Isa lead zinc flotation circuit – experiences from the implementation of model predictive control, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 101–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

Watershed Jll in Jefferson County, Ohio we instrumented in 1977 as one of three watersheds established for the purpose of investigating surface mining and reclamation effects upon local hydrology, sediment discharge, and sediment and water quality. Each watershed was less than 50-acres in size, and was in a different geologic setting within southeastern Ohio. Surface runoff and ground¬water levels were monitored. Samples were taken for sediment determination and chemical analysis prior to mining. Monitoring and sampling continued through the period of watershed disturbance caused by mining and reclamation activities, which began in May 1980 at Watershed Jll. A psuedo-postreclamation period followed the initial cessation of man-machine activity on the watershed. A second reclamation effort occurred in the fall of 1981 and was to be followed by a third in 1982 after observations ceased. A true final postreclamation period was not monitored at this site, because the erosion control practice (terrace diversions) failed after each reclamation. Watershed Jll was a small pasture and wooded watershed with sandstone and shale above the mined coal seam prior to mining. A clay layer under the coal supported a perched saturated zone, termed the top aquifer for convenience. A lower underclay supported a second saturated zone called the middle aquifer. A lower perched aquifer had been dewatered by previous deep mining. After about three years of premine data and about two and one-half years of mining reclamation and psuedo-postreclamation data, the following general observations may be made: 1. The mining-reclamation phase was very short, and the postmining period was characterized by erosion failures and remedial disturbances that kept the watershed condition and size in a state of change. It was impossible to collect sufficient data to confidently characterize the hydrologic-sediment-chemical aspects of the mining period or of a postreclamation period and, most importantly, of the future watershed after its various properties and characteristics have ceased adjusting to its severe disturbance and reconstitution. 2. A seeding of wheat followed by grasses and legumes was not a particularly successful reclamation practice in terms of stabilizing the new soil. Numerous rills and small gullies developed in spite of installed diversions. 3. Storm runoff rates and yields at the watershed outlet increased from the premine, (phase 1) to the mining-reclamation (Phase 2) periods, and remained at or near the Phase 2 level through the postreclamation (Phase 3a) period. 4. The top aquifer changed in physical and chemical character as a result of mining and was becoming reestablished as the project drew to a close; but it is impossible to predict its final configuration or character. 5. Dewatering of the top aquifer resulted in a complete cessation of baseflow because the middle aquifer water table lay below the elevation of the watershed outlet. 6. The top and middle aquifers were merged in one area of the watershed where the upper coal underclay was disturbed. 7. Failure of the diversion terraces and their outlet obscured the effects of the reclamation practice upon sediment concentration and yields. There was little difference in sediment concentrations between Phases 2 and 3a. 8. Drinking water standards were met by surface waters throughout the period of observation except for two samples that exceeded the nitrate-N allowable level of 10 mg/l. 9. In all Phase 3 surface-water samples, iron concentrations were within the limits established by OSM, and manganese concentrations exceeded the regulation level only once. pH fell below the lower regulation level of 6.0 between 10% and 20% of the time. 10. The chemical quality of sediments was generally about the same after reclamation as before mining, with the exception of organic carbon, which decreased.

Jan 1, 1983

By A. Gronningsater

Introduction As is well known, the fight between the blast furnace and the reverberatory furnace in copper smelting during the second decade of the century ended with a victory for the latter, a result which must largely be attributed to the introduction of flotation methods. To my knowledge, no new blast furnace has been blown-in at any American copper smelter since the War. As the metallurgy of nickel, up to and including matte smelting, is generally considered a close parallel to that of copper, the introduction of reverberatory smelting in the big new smelter of the International Nickel Company at Copper Cliff, built in 1928-30, seemed a logical adherence to a well established trend. In view of these facts, considerable comment was made when Falconbridge Nickel Mines decided to retain the blast furnace in their smelter built about the same time, in 1929. A presentation of the reasons governing this choice should therefore be of interest. The basic principles underlying the Falconbridge practice, and the considerations guiding the successive steps in the operations, will be discussed in the following. To understand the problems involved, the character and mode of occurrence of Sudbury ore must be kept in mind. Large amounts of disseminated ore are generally present. Although the gangue usually runs only about 50 per cent Si02, the ore hoisted as a rule contains more silica than needed in the smelting operation; until recently this excess was removed entirely by hand picking (in later years supplemented by magnetic sorting methods), a difficult and not very satisfactory method, in which 'the border line between ore and waste is entirely arbitrary, and therefore too much depends on the judgment of the picker.

Jan 1, 1934

By Peter F. Mataich

The phosphate mining industry is a highly competitive one, one in which survival depends on the plant's ability to produce at costs equal to, or below, the competition. The solution toward getting costs down is usually one of scaling up the plants to get the most tons through at the lowest possible cost. Control of these plants has been an art. Few of them are well instrumented because until a few years ago reliable instrumentation was non-existent. International Minerals and Chemical Corporation was a pioneer in applying computer techniques to ore reserves analysis and mine planning and the success in these areas led to the question of whether we could not extend the advantages of computer processing into the plant itself. There was a great deal of doubt on the operator's end that this could be done successfully because of the lack of instrumentation and the fact that plant control was largely an art that was learned only after many years of experience. However, in 1965 the instrumentation picture began to look up and the new generation of process computers just coming on the market were considerably lower in cost than the previous ones. A preliminary study of the installation costs and the probable benefits that could be realized from computer control convinced us that a process control computer should be seriously considered for a new phosphate mining plant which was being designed.

Jan 1, 1969

By F. Smit

Mining and plant disciplines can benefit from pre-concentration of UG2 platinum ores in a dense medium separation (DMS) plant. The main benefit of DMS is the selective discard of waste from the feed stream, thus improving project economics while reducing the power and water requirements for processing. On the mining side, with the correct combination of variables, implementing DMS as a pre-concentration step can reduce cut-off grades and, as a result, increase ore reserves. In addition, the use of DMS technology gives the mine team the opportunity to consider alternative mining methods for an operation. The challenges of balancing the mining tonnage, methods, and resulting grades with the process plant size, recoveries, and DMS discard volumes have resulted in the development of a model to optimize value on new projects or existing operations. This paper will focus on these benefits from a mining and plant perspective, quantifying the water and power savings, and look at the economic benefits of pre-concentration and the effect of metal prices, plant feed grade, and DMS efficiency in different mining environments.

Jan 1, 2012

By Patrick J. Maessen, Bart H. M. Hendrix

"In the Netherlands, the Dutch Tunnel Standard has been developed for the execution of road tunnel projects. The Dutch Tunnel Standard is based on the Dutch Tunnel Law (WARVW) which sets the minimum safety standard for road tunnels in the Netherlands. Uniformity of tunnels and the uniform perception of a tunnel by its users leads to a higher safety level. Therefore, several items in the Dutch Tunnel Standard are specifically developed to ensure safety in emergency situations through the plane of human factors. Taking human factors into account is important in regular traffic situations, but in an emergency situation, this can be vital. In this paper, the development and contents of the Dutch Tunnel Standard are explained in the first part and in the second part, the systems related to human factors are described. DUTCH TUNNEL LAW AND THE NEED FOR THE DUTCH TUNNEL STANDARD In the 90’s of last century and the early 2000’s, several serious accidents occurred in tunnels in Europe. These accidents involved fire and led to many casualties. After these accidents, the European Union decided to change the regulations for tunnel safety, leading to the EU directive 2004/54/EG. The primary goal of this directive is, that casualties are minimized in case of a calamity in a tunnel (e.g. fire). In the Netherlands, the EU directive led to the development of the tunnel law and a tunnel regulation (in 2006) to prescribe the safety features required for a safe tunnel. The new Dutch tunnel law – cited in the Building Act – was meant to make tunnel design easier – but resulted at first in the opposite effect. Tunnel design in the Netherlands and design standards of Rijkswaterstaat Rijkswaterstaat – the executing organisation of the Dutch Ministry of Infrastructure and the Environment – is the owner of the tunnels in the Dutch national motorway network, thus owner of the majority of the road tunnels in the Netherlands. In the early years of tunnel building in the Dutch national highway network (approximately 1950 – 1970), Rijkswaterstaat was not only owner, but also designer of its own assets. Most Dutch tunnels are submersed tunnels, because these type of tunnels provide a cost-effective way to make river crossings. Another type of tunnel that is used, is a TBM tunnel. Because of the geological conditions in the Netherlands (merely clay/peat and sand), there are no NATM or drill-and-blast tunnels in the Netherlands. Since the last decades, land tunnels (covered roads) are becoming more common to provide for multiple use of surface space and to meet more modern environmental regulations as traffic increases near densely populated areas. Tunnel lengths in the Netherlands vary from 500 m to 1.5 km for river crossings up to 6 km for the Western Scheldt (bored) tunnel. The lengths of land tunnels vary from 500 m up to 3 km. With these increasing lengths, some safety topics and design topics arise, topics that were non-issues in the past, when tunnels were only used as river crossings."

Jan 1, 2016

By C. Newman, R. C. Ray

Originated and developed in the civil tunneling industry, the Ground Reaction Curve (GRC) has provided a robust methodology for evaluating and designing ground support in both tunnels and underground mining scenarios. This paper presents a preliminary assessment in the utilization of the GRC concept for the evaluation and design of the pillar-support system with respect to overburden stress and displacement. This initial assessment will be based on and backed by past research on this topic. Underground mine instrumentation is planned for a longwall mine in the Appalachian coal field based on the research and findings in this paper to support the postulated hypothesis. INTRODUCTION Since the early 1970’s, the mining industry has evaluated the structural stability of a pillar by dividing an approximated pillar load by an approximated pillar strength. While this design methodology has served the industry well in the past, as modern mining operations continue to develop in more complex geological and geometric conditions coupled with market economics, industry professionals are in dire need of a modified stability assessment approach which considers both the stress condition and material displacements. Within the civil tunneling industry, the GRC approach has been successfully utilized in designing underground support measures that enhance the stability of an underground excavation. Through the incorporation of current industry knowledge and understanding of ground and support behaviors this paper looks to investigate into preliminary assessment for the development of a Modified Support Response Method (MSRM) to further improve the analysis of local and global underground stability. CURRENT PILLAR DESIGN METHODS AND THEIR LIMITATIONS Globally, multiple pillar design methods have been utilized in the design of underground excavations. Each of these methods approaches the calculation of pillar stability a little differently with respect to material properties, underground geometries and stress conditions. Analytical solutions can be used to determine the strength of homogeneous materials like concrete, but not in case of non-homogeneous and non-isotropic mineral deposits in a mine. These equations are often derived using empirical methods. Pillar strength is defined as the maximum resistance of a pillar to axial loading (Brady & Brown, 1985). The strength of mine pillars is typically estimated through indirect methods. In the past, researchers have correlated the strength of a given size and width of a rock specimen to the strength of a mine pillar. The first study on the effect of geometry on rock strength was done by (Bauschiger, 1876) on Swiss sandstone samples. Since then several empirical equations to determine pillar strength had been published by many researchers like (Bunting, 1911), (Griffith & Conner, 1912), (Greenwald, Howarth, & Hartmann, 1939), (Holland & Gaddy, 1957), (Evana, Pomeroy, & Berenbaum, 1961) and (Holland C. , 1964).

Jan 1, 2019

By P. N. Mohan Das, K. Harikrishna Bhat

"The major ilmenite reserves are located in India at Chavara (CH), Manavalakurichi ( MK) and Chatrapur, Orissa (OR). India stands first in terms of ilmenite reserves, which are estimated to be 278 million tonnes out of which, 142 million tonnes are processable. Mineralo-chemical analysis shows that Chavara ilmenite is the most weathered one with about 60% TiO2 while Chatrapur is the least weathered with about 50% TiO2. Co-existence of ilmenite with pseudorutile, rutile and haematite is observed in substantially varying amounts in the three deposits. It is observed that the tropical weathering rather than the source rock difference has apparently played an important role in imparting major compositional and structural dissimilarities among ilmenites in different places.In processing of ilmenite through the Becher process, aeration rusting of pre-reduced ilmenite is found to be the rate limiting step thus, affecting the productivity of the process. Investigations have proved that the addition of some organic compounds such as glyoxal, sucrose etc., to the system accelerates the reaction to such an extent that the rusting time has been reduced to less than half.A new route of processing ilmenite for synthetic rutile has also been developed in which, ilmenite is carbothermally reduced and then processed through plasma route. The slag thus obtained is processed further to get high-grade synthetic rutile, metallic iron and high purity iron oxide. The process has been scaled up in a continuous moving bed plasma reactor. It is technologically and economically more viable where, all the iron values are recovered as salable byproducts. This paper describes the salient features of the technologies developed for the beneficiation of ilmenite to synthetic rutile."

Jan 1, 2003

By H. Foster Bain

The war has brought about many changes in the Western States, and some have deep pr sent or potent al economic significance. The West has been feeling severe growing pains for a number of years. Especially since the beginning of preparation for national defense and through the period of

Jan 1, 1945

By Ali Naeimipour

Availability of accurate geological information about the rock mass surrounding a tunnel or mine working is the key to enhance and optimize the required ground support measures. Various approaches have been used to obtain data on ground conditions, including the possibility of characterizing the ground while drilling for roof bolts, by the Measurement While Drilling (MWD) system, via optical, sonic and acoustic televiewers, and using various types of gamma probes. While there are many different systems for characterizing the ground in longer, larger-diameter holes drilled downward, the options for using probes and logging systems in short, small-diameter holes drilled in horizontal or an upward direction are very limited. This paper will present the results of recent field tests using optical televiewer (OPTV) to analyze the joints and voids in boreholes drilled in different directions. The studies show that OPTV is a promising tool; however, getting a good quality image from the upward drill holes still need to be studied. Meanwhile, estimated in-situ strength of the intact rock is needed to complement the jointing pattern for rock mass classification. For this purpose, preliminary steps for the development of a borehole scratcher to estimate rock strength will be discussed in this paper.

Jan 1, 2014

By Christopher Mark

Colombia is 11th largest coal producing nation in the world, and the world?s fifth largest coal exporter. But while most of Colombia?s coal is mined at large modern surface mines located near the Caribbean coast, there are also underground mines that produce high-grade metallurgical coal. These mines employ traditional hand-loading techniques in a variety of geologic environments, and they have some of the highest accident rates of any Colombian industry. The National Institute for Occupational Safety and Health (NIOSH) has been collaborating with POSITIVA, the primary provider of worker?s compensation insurance to the Colombian underground coal industry, to reduce the economic and social cost of rock falls in these mines. The specific goals of the collaboration are to 1) document practices and conditions in Colombian underground coal mines, 2) identify relevant international best practices, and 3) provide recommendations for developing a national campaign to reduce fatalities and injuries associated with roof falls. NIOSH conducted a survey of seven underground coal mines in four separate coalfields. Five of the mines were characterized by steep dips and weak roof and floor rock. The coal was loaded by hand at all seven mines, though two employed partially mechanized longwall techniques. Wood posts were by far the most common ground support. Roof bolts were not observed in use at any of the mines, and they are unlikely to replace timbers any time soon. While long-term entries generally appeared to be adequately supported, the survey found that less attention was paid to the temporary support that is installed right after the coal is removed. This temporary support is critical for protecting the workers from rock falls, however, because with hand-loading mining methods most of the activity takes place between the permanent supports and face. The study concluded that improving the temporary support in the working faces would be the most effective way to reduce the number of rock fall injuries. The key principle should be that every worker is protected by planned roof support at all times. Ground Support Management Plans, consisting of specific rules about when, where, and what roof support is to be installed, should be the focus of the campaign. Each Plan should be tailored to a specific mine based on the geologic conditions and mining methods in use. The Plan provides miners with clear, simple rules that can be easily understood, while management can easily check to see if it is being followed. Ground Support Management Plans will also provide the campaign with a concrete focus for the necessary cultural change.

Jan 1, 2014

By Robert L. Martin, Brian W. Stump

"The Black Thunder Mine is located in the Powder River Basin of Northeastern Wyoming. Over 39.2million tons of coal were produced at the Black Thunder Mine in 1996. Just over 100 million pounds ofANFO/Emulsion blend were consumed in that same year. Currently around 30% of the overburden is cast to final with the use of explosives. With plans for a mine expansion, explosives will continue to play a very vital roll well into the future."

Jan 1, 1997

By Francisco J. Sotillo

Using new ecological-natural-organic depressant for gangue and pyrite with antibacterial properties (control of acid mine drainage) with new improved xanthate collectors using rheology additive not chemical reacting with xanthate resulted in better sulfide flotation. Rougher-scavenger lead flotation tests were conducted increasing the concentrate grade from 7.07% Pb to 13.44% Pb, enhancing selectivity. Lead recovery increased from 64.08% to 79.38% and 80.40% using only the new depressant, and improved xanthate Z-11 and Z-4, respectively. The results demonstrated that the new depressant was selective and efficient, and the new improved xanthates stronger more selective collectors.

Feb 22, 2026

By Luís Marcelo Marques Tavares, Gilvandro Bueno, Túlio MoreiraCampos

The HPGR development and application in the minerals industry resulted in an important increase in its application in iron ore pellet feed processing in the last decades. Vale SA was one of the pioneers in application of the HPGR in integrated plants, currently operating with six HPGRs in the pelletizing plants of Complexo de Tubarão (Vitória, ES). The work uses the mathematical model of the HPGR, proposed by Torres & Casali and modified by the present authors, to predict the performance of two industrial pellet feed HPGR units of the Complexo de Tubarão. Besides model validation, results of process simulations are shown in order to optimize the pellet feed pressing according to industrial demands, presenting different scenarios that are more attractive to HPGR operation. Simulations showed that it is feasible to reduce the specific surface area of the HPGR feed from 1770 cm²/g to 1570 cm²/g, allowing to produce a pellet feed of the same quality in its product (1911 cm²/g) and therefore reduce the work done by upstream ball milling.

Oct 1, 2019

By E. Tabosa, S. Vianna, K. Duffy, W. Valery, B. Andrade, L. Pyle, P. Holtham

Pneumatic flotation cells are high-intensity flotation machines with rapid kinetics, resulting in short residence times. Examples include the Jameson, PneuFlot and ImhoFlot cells. These cells do not use impeller-like mechanical cells. Rather, the air and pulp are mixed in a continuous stream of high fluid velocity through a downcomer or venturi to disperse the air into fine (approximately 0.5 mm) bubbles and maintain particle suspension. Froth wash water is often used to enhance concentrate grade, minimising recovery by entrainment. With the growing application of these types of cells, not only in cleaner stages (their traditional use) but also in pre-flotation and scalping duties, there is a need to predict their performance more accurately for circuit design and optimisation. No widely accepted model for pneumatic flotation cells is available and their metallurgical performance is often scaled up from laboratory and/or pilot plant testing by assuming fixed values for metal recovery, concentrate grade and concentrate percent solids. This paper describes a new approach to simulate pneumatic flotation cell performance and presents case studies demonstrating its applicability. Keywords: Pneumatic flotation, flotation modelling, flotation circuit design, flotation circuit optimisation, Jameson cell

Jan 1, 2020

By Fred Leonard

This report is principally concerned with the engineering and economic feasibility of area surface coal mining systems other than draglines. This analysis evaluates shovel/ trucks, shovel/crusher/conveyors, and shovel/rail excavation and haulage systems for an assortment of geologic environments and production rates in the Powder River Basin (PRB) Shovel/trucks, front-end loaders/ trucks, and shovel/crusher/conveyors were studied in a multi-seam, dipping geologic area of the Four Corners Region. The Texas lignite engineering and economic research involved bucket-wheel excavators (BWE), BWE/backhoes, and scraper/backhoe combinations for overburden and coal excavation. The PRE truck/shovel study utilized the most recent computer simulation available in both the design and cost analyses. Detailed engineering analysis, followed by in-depth operating costs (operating and depreciation) result in a complete evaluation of each mining system. Cost comparisons of the different mining systems under similar geologic and production constraints are presented in the report to illustrate the estimated capital investment and production costs per ton of coal and bank cubic yard of overburden.

Jan 1, 1980

By Djona M. Gaballah I.

Selective chlorination of unroasted and roasted spent hydrorefming catalysts was studied between 300 and 600°C using the following gas mixtures : C12+CO, C12+N2 and CI2+air. Such materials contain Co, Ni and Mo compounds supported by alumina and/ or silica. They also contain variable amounts of V compounds, C, S, etc., accumulated during the life time of the catalyst. Direct oxychlorination of the C+S rich sample allows higher extraction rates than those obtained by the carbochlorination of the same roasted one. It seems that the roasting step doesn't favor the economic metals' recovery. Results of the chlorination of C+S poor spent catalysts, in the presence of CO, in the chlorinating gas mixture, or of carbon added to the sample, were comparable. Cobalt and nickel chlorides were .extracted from the chlorination residues by their dissolution with acidified water, whereas molybdenum and vanadium chlorinated compounds were recovered by selective condensation from the vapor phase. The recovery rates of valuable metals as well as the selectivity were higher for the chlorination of spent catalysts than results obtained by the hydrometallurgical processing of the same sample. Results of the scale-up of the oxychlorination of the unroasted sample confirmed those of the laboratory scale. The global recovery rates were about 88 pct of cobalt, 93 pct of molybdenum and 76 pct of vanadium. The carbochlorination was applied to the recovery of W and Ti from Denox catalyst that is a carbon and sulfur free one. Recovery rates higher than 99 pct at temperatures lower than 500 °C could be obtained. This may indicate that the chlorination process can be applied to the treatment of various industrial wastes or by-product containing transition and/or refractory metal compounds A flow - sheet for the pretreatment of these materials is proposed.

Jan 1, 1995