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By Helge Rosenberg

Up to now, Topsøe WSA (Wet gas Sulphuric Acid) plants have been in operation for almost 30 years, and close to 80 plants have been sold. In spite of its unique features and ability to treat gases without any prior drying, the WSA technology has had certain restrictions with regards to SO2 concentration in the feed gas, and the overall conversion of SO2 by catalytic means has been limited to approx. 99.7%. In commercial scale sulphuric acid production on the basis of elemental sulphur and metallurgical off-gases, there is a demand for higher SO2 conversion and treatment of gases with a higher content of SO2. Therefore Topsoe has further developed its WSA technology to cope with these demands. This paper will explain more about the principles of such new development and leave the delegate with a better understanding of the potentials of the new generation of the WSA technology from Topsoe.

Jan 1, 2009

By Helge Rosenberg

Up to now, Topsøe WSA (Wet gas Sulphuric Acid) plants have been in operation for almost 30 years, and close to 80 plants have been sold. In spite of its unique features and ability to treat gases without any prior drying, the WSA technology has had certain restrictions with regards to SO2 concentration in the feed gas, and the overall conversion of SO2 by catalytic means has been limited to approx. 99.7%. In commercial scale sulphuric acid production on the basis of elemental sulphur and metallurgical off-gases, there is a demand for higher SO2 conversion and treatment of gases with a higher content of SO2. Therefore Topsoe has further developed its WSA technology to cope with these demands. This paper will explain more about the principles of such new development and leave the delegate with a better understanding of the potentials of the new generation of the WSA technology from Topsoe.

Jan 1, 2009

By D Craw

Bulk ore tailings from the Macraes gold mine gold extraction process are stored in a large (ca 0.6 km2, 80 m deep) mixed tailings impoundment whose pH is maintained near 8 by natural rock neutralizing capacity. The mixed tailings will be stored in this impoundment in perpetuity after mining ceases. Confidence in the long term environmental stability of these tailings can be gained from examination of mineralogically and chemically similar geological situations in the immediate vicinity. A sequence, typically about 5 m thick, of sands and gravels derived from the Macraes mineralized zone 12 000 to 28 000 years ago contains rounded detrital sulphide mineral grains which are unoxidized despite close proximity to the surface and occasional incursion of oxygenated waters. Saturating water pH is currently 7-8. Sands with 0.2 to 0.8 wt % organic carbon host sulphate-reducing bacteria (SRB), and localized cementation by authigenic framboidal pyrite has occurred. Comparison of the 28 000 year-old sediments with the modem tailings suggests that similar chemistry will prevail, possibly with deposition of authigenic pyrite in the tailings, in the long term. As long as the present slightly anoxic and circumneutral pH environmental conditions are maintained in the mixed tailings dam, sulphide decomposition and acidification are unlikely. These sediments provide a plausible geological analogue for long-term benign storage of the mixed tailings impoundment.

Jan 1, 2000

By J. R. Nettle

The development of a process for upgrading offgrade titanium metal by electrorefining in molten salt led to an investigation of the electrotransfer characteristics of selected metals when alloyed with the titanium to be refined. Previous tests on seven binary titanium alloys showed that the degree of transfer of the alloying constituent depends on the constituent and on the operating procedurese.5 This report describes tests on electrorefining ternary mixtures of titanium with selected metallic elements. Ten alloys were prepared from high purity titanium and 2-1/2 percent of each of the metal pairs selected from the same elements used in the binary study; manganese, vanadium, chromium, zirconium, tin, molybdenum, aluminum. Operating variables were similar to those investigated in the binary alloy study that gave minimum alloy metal transfer. The data presented indicate the transfer characteristics of the various metals and combinations tested relative to each other.

Jan 1, 1962

By Marcia Harris, Richard Mainiero, Michael Sapko

Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings and one fatality. To better understand the factors contributing to this hazard, the National Institute for Occupational Safety and Health (NIOSH) carried out studies in a 12-foot diameter sphere to identify key factors that may enhance the levels of CO associated with the detonation of several commercial trenching explosives. The gaseous detonation products from emulsions, a watergel, and ANFO blasting agents as well as gelatin dynamite, TNT, and Pentolite boosters were measured in an argon atmosphere and compared with those for the same explosives detonated in air. Test variables included explosive formulation, wrapper, aluminum addition, oxygen balance, and density. Major contributing factors to CO production, under these laboratory test conditions, are presented. The main finding is the high CO production associated with the lack of afterburning in an oxygen poor atmosphere. Fumes measurements are compared with the manufacturer’s reported IME fume class and with the Federal Relative Toxicity Standard 30 CFR Part 15 in order to gain an understanding of the relative toxicity of some explosives used in trench blasting.

Jan 1, 2003

By A. E. Raddatz

In an attempt to develop technology to use domestic resources in place of imported bauxita, the Bureau of Mines investigated sulfurous acid leaching to extract alumina from kaolin. The process consists of leaching the calcined kaolin with a 30 wt-pct S02 solution at 60° C and 160 psig for 17 hours, fil¬tering the leach slurry, precipitating monobasic aluminum sulfite from the filtrate at 110° C and 60 psig, a& decomposing the sulfite in the spent liq¬uor at 150° C and 55 psig to produce crude alumina. Purification of the crude alumina was accomplished using a modified Bayer process. Results from closed-circuit tests employing the sulfurous acid process showed that overall extraction of alumina from kaolin was 67 pct. Production of 1 ton of alumina would require 3.6 tons of calcined kaolin, 0.7 ton of sul¬fur dioxide, and 8.4 tons of water. After purification by a modified Bayer process, the alumina product contained the following; impurities, expressed in weight-percent: Fa203, 0.009; S, 3.6; Si02, 0.07; Ti02, 0.002; K20, 0.017; and P205, 0.03.

Jan 1, 1981

By K. Bartholomew

The Functional Performance Equation for ball milling circuits provides plant staff with a new means to improve circuit performance. However, successful execution of a plant processing performance improvement project, with verifiable improvements, requires a significant number of accompanying steps beyond using this equation. In order to identify and articulate all these steps, a study was undertaken with the metallurgical staff from two milling operations and process application specialists from a grinding media manufacturing company. “Task analysis” of improving plant grinding performance was carried out. This analysis identified the required steps, and ultimately yielded a “Plant Grinding Circuit Processing Performance Management/ Improvement System.

Jan 1, 2015

By Donald Leroux, Dave Scott, Giovanni Di Prisco

"The Lady Loretta lead-zinc deposit in Northwest Queensland, Australia contains an average of 5.9% lead, 17.1% zinc and 97 g/t silver. Ore mineralization is mostly comprised of fairly complex intergrowths of pyrite, sphalerite and galena. Starting in 1998, Noranda Inc., the major joint venture partner of the project, conducted extensive metallurgical test work, which culminated in July - August 2000 in a series of Pilot Plant tests. A common thread to all the metallurgical work has been the deportment of a large portion of silver into non-payable metallurgical products. Average silver distribution from four Pilot Plants shows a distribution of silver in lead concentrate of 28%, whereas silver in zinc concentrate was 49%, and 23% in the final tails.The consistently poor silver recovery as well as the fairly unusual silver distribution, particularly in zinc concentrate, was considered an issue to be thoroughly investigated. A mineralogical plan was devised to determine if these particular metallurgical results were somewhat related to the nature and mode of occurrence of silver carriers. Work was performed to determine discrete silver-bearing minerals and/or silver contained in solid solution in a suite of commonly occurring sulphides. Ore microscopy, SEM methods, Electron Microprobe and Ion Microprobe analyses were all used to answer these questions, and to find the silver carriers, so a metallurgical plan could be devised to improve silver recovery.INTRODUCTIONPotential economic exploitation of the Lady Loretta deposit in Queensland, Australia is driven by revenue derived from zinc and lead flotation concentrates and co-product silver recovery in lead. Relatively low recoveries of payable silver to lead concentrate, and high silver distribution to zinc concentrate necessitated an investigation into the natu"

Jan 1, 2002

By S. Devasahayam

Acid production or acid drainage is a major environmental issue that also has negative implications on the aquifer system surrounding the mine tailings area. The approach to controlling acid mine drainage involves physical and geochemical characterization that affect acid production. The material permeability determines the availability of oxygen, which is paramount in acid production in coal rejects, and varies with depth. In this paper the author presents the variation in oxidized pyrite/acid production with depth in black coal mine washery wastes. Chemical kinetic parameters and the diffusive parameters have been used to obtain the variation in oxygen content and the oxidized pyrite content with respect to the depth and time. Its dependence on porosity and moisture content is illustrated.

Jan 1, 2007

By J. A. HUFF, V. V. BAKER

This circular is intended to present in brief form the statutory provisions of Pennsylvania regarding mining operations, in force at the end of the 1931 session of the legislature. lo reference is made to general laws which affect mining only incidentally in common with other subjects, such as the workmens compensation law. The statements have been condensed as far as practicable, and provisions not deemed of general interest, such as matters dealing only with administrative details, have been omitted. This circular obviously is not written with such particularity as to be of great value to the legal profession, but it is hoped that it will be beneficial to the mining industry in giving this information in a relatively compact form. At the end of each paragraph the statute from which it is derived is cited to facilitate reference to the text of the law. It is planned to publish additional circulars from time to time dealing with the mining laws of other States. Any criticisms of the form of publica- tion followed herein, or suggestions aimed at the improvement of future circulars, will be welcomed.

Nov 1, 1932

By J. F. Jackson, R. W. Mau

"The first commercial installation in the mineral industry of the ""Verti-Press"" pressure filter was made by Falconbridge Limited at the Strathcona Concentrator to filter copper concentrate. The filtercake produced contains 6 - 7% H2O, an improvement from the 12 - 13% H2O produced by an internal drum filter, at rates of up to 20 t/hr. A novel slurry feed system incorporates a hose pump and a pressurized slurry accumulator.INTRODUCTIONIncreased copper production from Falconbridge Limited operational mines in the Sudbury Area has exceeded the current refinery capacity. A copper concentrate has been produced to overcome this constraint and has been shipped to custom smelters either as a slurry or as a 12 - 13% moisture filtercake utilizing an internal drum filter.With the treatment of the new Deep Copper Zone from the Strathcona Mine, copper concentrate production was forecast in excess of the installed dewatering capacity. The filtercake was too wet to transport by truck and the custom smelter refused to handle this product at the truck unloading site. The filtercake had to be trucked to a rail spur and transloaded into gondola cars. This system was expensive, incurred unaccountable losses and the concentrate was assessed a moisture penalty.To reduce the concentrate moisture content to permit direct shipment by truck, two basic systems were available; vacuum filter followed by a thermal dryer or a pressure filter. Past experience with the high capital and operating costs of dryers led Falconbridge to closely examine the pressure filter alternative.COPPER CONCENTRATE PRODUCTIONThere are two separate circuits at the Strathcona Mill; one treating nickel ore and the other treating copper ore.The rougher concentrates produced by both circuits are conditioned with lime and cyanide before the copper-nickel separation in a flotation columns. The concentrate consisting of cha lcopyrite with mi nor cubanite is very clean as shown in Table I. Currently 50% of the copper in the plant feed reports as copper concentrate, in the past, this has been as high as 70%."

Jan 1, 1990

By Virgil A. Marple

It was the purpose of this contract to conduct research in several different areas of instrumentation used to determine the quantity of respirable dust in the mining atmosphere. One area of research was in evaluation of instruments including several respirable dust monitors, several types of photometers, and a QCM cascade impactor. An instrument evaluation chamber was developed to aid in evaluating the instruments in a dust atmosphere. Another area of research was investigations into new instrumentation concepts, such as a virtual impactor/photometer instrument, a new optical device which can be used as either an optical particle counter or photometer, a new personal respirable sampler, which employs an impactor instead of a cyclone as a preclassifier, and the development of a new cascade impactor, which deposits the particles uniformly on the impaction plate. Another area of research included the use of many of these instruments in two field studies, including a silica sand plant and a tungsten mine.

Jan 1, 1981

Possibilities and Working of the Specific Agglomeration of Fibrous Materials and Residues Plant based fibrous materials are becoming of increasing interest in a multitude of industrial applications. Main advantages are the specific lower energy demand and virtually closed CO2 cycle, excellent mechanical properties based on low density as well as a high level of recyclables. In contrast, processing and handling of such materials is associated with a number of challenges. These challenges are mainly related to specific morphological characteristics in correlation to fibre length and structure (branching and splices). Specific problems in further processing steps including transport, dosage or storage for natural fibre compounding, result from form-locking bonds leading to burling, clusters or plaits. Technologies of fibre processing are well known, but other than textile based technologies they generally result in intermediate goods which do not allow direct industrial application. The investigation to be presented is based on results of recent research activities and shows two possible technical solutions of innovative fibre agglomeration procedures. These methods allow the conversion of middle to long fibres into a form, which eases further processing and dosage significantly and therefore allows free flowing too. The procedures are based on the working principles of rolling and winding technology. Within the work, both of the patented methods and their respected lab-scaled devices will be described. Further, results will be shown for an up-scaled rolling agglomeration unit applying the developed principle and consisting of multiple process zones. Possible variations of the resulting product characteristics and the impact of different process parameters will be discussed based on the trials with natural fibre (hemp and flax) agglomeration. As a main outcome of the research, product qualities can be supplied according to the requirements of the specific application in correlation to agglomerate strength, porosity or form. In conclusion, recent developments for specific methods of characterization will be depicted.

Sep 13, 2010

By M. Yavuz

Multiple Criteria Decision Making (MCDM) is one of the most considerable branches of Operation Research. MCDM refers to making decisions in the presence of multiple, usually conflicting, criteria. The problems in MCDM are classified into two categories: Multiple Attribute Decision Making (MADM) and Multiple Objective Decision Making (MODM). However, very often the terms MADM and MCDM are used to mean the same class of models and mostly confused in practice. Usually, MADM is used when the model cannot state in mathematical equations and otherwise MODM is used (Hwang and Yoon, 1980). Decision-making (DM) is extremely important stage in Mining Engineering like other engineering branches. Every mining engineer makes several decisions in daily mining applications. Most of the decisions made by mining engineers are completely instinctive according to their past experiences and there is not any DM method applied in DM process. Analytic Hierarchy Process (AHP) is one of the well-known techniques solving the decision problems. The AHP is very simple, and understandable method especially non-numerical data considered in DM process. Equipment selection is one of the prominent problems of mining engineering. Mining engineers have to make difficult decisions when equipment selection stage. As the decisions in the equipment selection have radically influenced the economic life of any mining scenario, these are considered as complex MADM problem. So, the decision maker can evaluate the subjective criteria in the problem of equipment selection. The decision maker wants to maximize more than one objective criterion for equipment selection stage. Among the number of alternatives, the most suitable equipment must be selected according to objectives and alternatives. MADM applications can help the decision maker to reach the optimal solution for the equipment selection. In the mining industry, MADM methods can be applied for the equipment selection because it is a process that includes subjective and objective criteria affecting the selection of equipment among the alternatives.

Jan 1, 2007

By D. Nyembe, B. Mamba, Antoine F. Mulaba-Bafubiandi

Copper and cobalt are generally electro-won from their aqueous sulphate solutions. After optimised leaching of their ores, concentrates or calcine bearing minerals, the leachate is clarified and suitably purified prior to the electrolytic extraction of the metal of pursuit (Pearcy, 2006). Solvent extraction (SX) using appropriate organic solvents and ion exchange (IX) with relevant resins are known purification processes used for copper and cobalt recovery (Stanely, 1970).As zeolites in general and natural zeolites in particular, demonstrate ion exchange properties (Korkuna et al., 2005), an attempt has been made to use Southern African natural clinoptilolite in the recovery of copper and cobalt from their aqueous sulphate solutions. Initially, synthetic Co and Cu solutions were prepared. Preceded by laboratory ore leachate, plant solutions are to be used. AAS, XRF, XRD, Mossbauer spectroscopy and BET were characterization techniques used. Natural clinoptilolite was used as-received as well as acid activated; and cobalt and copper extractions were performed at room temperature.

Jan 1, 2007

By Pablo González, Rodolfo Espinosa, Jose-Luis Noyola, Sergio Cossio

"Minera Penmont, at La Herradura, is a joint venture between Industrias Peñoles, S.A. de C.V., and Newmont Mining Corporation. The mine is located in the northern Mexican state of Sonora. La Herradura consists of an open pit mine with two-stage crushing and heap leaching facility, the gold is recovered from the pregnant solution using the Merrill-Crowe process; production began in July 1998. La Herradura produces about 130,000 gold ounces per year, and treatment capacity is 22,000 tonnes/day. Ore mineralization occurs in a shear zone with quartz and native gold. Gold distribution is quite heterogeneous due to the coarse visible gold, in some coarser particles ranging from 100 to 600 microns.Sampling and assaying protocols where established during exploration and prior to starting up operations, based on nomographs developed from early heterogeneity tests. But, as the coarse gold problem became noticeable, it was necessary to develop new sampling protocols to have an acceptable relative standard deviation to control the fundamental error within ± 15%.An experimental program was developed and conducted on a selected ore block made of 195 blastholes; regular ore grade control procedures were applied to both sets of data to evaluate the difference in results between the protocol established prior to starting up operations (“existing”) and the new protocol (“leaching”). In the “existing” protocol, subsampling is done through riffle splitters, and coning and quartering. Fire assaying is used to estimate the gold content, on a 50 g sample. In the “leaching” protocol a 12,000 g sample was bottle rolled cyanide leached, and the leach residue was assayed on a 50 g sample using fire assaying, and a weighted average total gold content was calculated. Currently, a new alternative method is being evaluated, where sub-sampling is done using rotary splitters, and fire assay on a 50 g sample; in this “rotary sampling” protocol and for comparison purposes, gold assays were also repeated using the “leaching” protocol.Test results were compared in three groups < 0.30 g/t (below cut-off), 0.30 to 0.8 g/t, and >0.8 g/t. Overall. Results show that the protocol established prior to starting up operations underestimates the gold assays. Detailed technical results, alternative options, and their implications are discussed in the paper."

Jan 1, 2003

By D. A. Bruce

To check the feasibility and the quality of a very deep diaphragm wall, a tern of adjacent panels has been constructed, up to a depth of 100 m, in the Milan sandy gravelly soil by means of a hydraulically driven milling machine with reverse circulation of mud. The results of the monitoring carried out in order to evaluate the panel geometry and the quality of both joints and concrete are described. The use of instrumentation based on different physical principles allowed the cross checking of measurements as well as the evaluation of the accuracy and sensitivity of each single procedure to be performed. The trial field was successfully carried out and the feasibility of a diaphragm wall of such a depth was demonstrated and corroborated by a reasonable level of quality control.

Jan 1, 1989

Several years ago, Hudco Industrial Products began experimenting with the idea of levitating a conveyor belt with a film of air, much like the puck on an air-hockey table. While conducting its research, the company found out that some Russian and Dutch companies attempted the concept during the 1970s. After studying those conveyors, Hudco determined that its design was better. The Hudco advanced air-supported conveyor consists of an air-tight plenum, or chamber, that runs the length of the belt. The topside of the plenum has a formed trough. It corresponds to the profile of conventional troughing rollers. Low-pressure air is provided to the sealed plenum from a low horsepower blower. This pressurized air is metered and released through the central portion of the trough and reacts against the underside of the belt. The differential pressure between the top and bottom surfaces creates the lift to support the loaded belt. Airtight covers are installed to seal the transported materials in the plenum trough.

Jan 1, 2002

By H. C. L. Reemeyer

"The mining industry faces increasing economic, environmental and social challenges, as easier deposits deplete and ores become more difficult to mine and process; head grades decline; projects migrate to increasingly remote and difficult geographies; and the industry faces more stringent environmental and social standards. While these factors increase costs and risks, they also present opportunities for a more integrated approach to mining, processing, materials handling and waste management. Two key areas of risk are in tailings and water management. As mining and processing tonnage rates continue to increase, the disturbance footprints, water and energy consumption and scale of tailings storage facilities also rise. These factors can be mitigated by more selective mining, ore sorting and pre-concentration, and more intensive tailings dewatering. Such alternatives must be considered in conjunction with the selection of mining method, metallurgical flowsheets, major equipment selection, and key process design criteria. For example, increasing the grind size of a concentrator reduces energy consumption and eases tailings dewatering, but may cause challenges with metal recovery. Emerging technologies will be reviewed, and economic and environmental trade-offs for eco-efficient alternatives will be presented for metal sulfide mines.INTRODUCTION The metals mining industry faces significant challenges that can affect its financial viability and social license to operate. There has been a consistent decline in ore grades and a relentless push towards larger operations to capture perceived economies of scale. With these larger operations, the environmental footprint of mines has increased. Water and energy consumption, and resulting GHG emissions have also risen. In recent years, two issues have raised special concerns for stakeholders and companies: • Water scarcity, particularly in drier regions of the world such as Northern Chile, SW USA, Southern Africa and Australia • Tailings risks, following the high-profile failures of the Fundao tailings dam in Minas Gerais, Brazil in 2015 and the Mount Polley tailings dam in BC, Canada in 2014"

Jan 1, 2017

By M Dalm

More and more mining companies are becoming aware of the potential benefits of sensor-based ore sorting and process optimisation. This is reflected by a growing number of analysers that are available for drill hole logging, conveyor belt scanning, ore sorting, slurry analysis, etc. These tools all rely on a specific sensor technology that can be used to detect a material property such as colour, density, mineralogy, or chemical elements. However, all sensors have restrictions on the minerals and/or elements that can be detected or inferred. This is caused by the physical mechanisms behind the technology and depends on mineral concentration and compositional heterogeneity of the ore. Since nearly every ore deposit is unique in composition and characterised by different geological features that drive heterogeneity, no one-size-fits-all sensor solution is available. This makes it difficult for mining professionals to find suitable sensing technologies that can help them solve problems and improve processes for their specific ore types.

Sep 1, 2024