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By Daniel Magill, Jim Gentry

"Acrylamide chemical grout (C3H2NO) has been successfully used for over 50 years to control groundwater and stop infiltration. This paper will address three unique projects involving the control of groundwater with each study providing special circumstances and geological conditions: encapsulation of radioactive hazardous waste in the United States, a tailings dam for a large copper/gold mine in Argentina and 27 miles of leaking subway in Canada. The primary reasons for selecting acrylamide grout were based on the following characteristics: thinnest chemical grout on the market, a true solution grout which contains no suspended solids in the blended product, flexible gel set times, and a 362 year half-life in soil as determined by the U.S. Department of Energy.INTRODUCTIONChemical grouting has been successfully used for over fifty years to control the movement of groundwater in a wide variety of applications including:•, Hazardous Waste Containment•, Subways & Tunnels•, Mines & Tailings Dams•, Concrete & Earthen Dams•, Underwater Structures•, Beneath/Around Underground Structures•, Mainline Sewers, Laterals, Manholes•, Large Soil Stabilization ProjectsThis presentation will review three projects where chemical grout was utilized to address some very difficult water control challenges, each providing special circumstances and geological conditions:1. Pre-construction seepage control at a mine tailings dam2. 27 miles of leaking subway3. Encapsulation of radio-active hazardous wasteThe reasons for selecting acrylamide grout as the solution for controlling groundwater in these selected projects were based on the following characteristics:1. Acrylamide grout is the thinnest chemical grout on the market2. No suspended solids which allows acrylamide grout to travel anywhere water can travel3. Flexible gel set times from 5 seconds to 10+ hours4. U.S. Department of Energy studies conclude that acrylamide chemical grout has a 362 year half-life in soil and can reduce the permeability of rock/soil to less than 10-8 meters per second (m/s)"

Jan 1, 2017

By Charles A. Mitke

The Copper Queen mine is composed of seven divisions which are operated through the following shafts: The workings of the different shafts are connected by motor-haulage drifts on the even numbered levels. The general location of the ore-bodies and workings is illustrated by the vertical projection of orebodies of the district as shown in Fig. 1. The Uncle Sam, Southwest, and Czar workings have many connections to the surface through raises and extensive cracks that were caused by moving ground. These divisions are cool and are ventilated entirely by natural means. The Holbrook is ventilated partly by natural and partly by artificial ventilation, while the Spray, Gardner, Lowell, and Sacramento are ventilated entirely by mechanical means. In some of the divisions mentioned above a considerable quantity of air exhausts through shafts of adjoining properties.

Jan 1, 1916

By C R. Ferrari

Residual subsidence is generally accepted as being about 5% of the total subsidence occurring within 12 months of all mining finishing. This paper looks at five case studies from different parts of the country, in various mining settings within a depth range of 430m to 760m. From a single seam single panel working to working the eleventh seam, all are within the concealed coalfield, similar to today's mining. The monitoring of subsidence continued for many years once the mining had finished and the results obtained are at considerable variance from the accepted norm. Subsidence has been found to carry on for up to eleven years after mining has ended, within a range of 8% to 45% of total subsidence. A highly significant factor was that subsidence, as a whole, was generally much more than predicted. The residual subsidence aspect has to he viewed in this context and in order to debate the subject at length, the causes of residual subsidence have to be balanced against the apparent inability to accurately predict subsidence. The results from the case studies were similar, even though the mining settings differed considerably. Subsidence of around 10% to 20% continued for several years after mining had ceased.

Jan 7, 1997

By Stephen P. Holt

During the spring and summer of 1946, the Bureau of Mines put down 8 churn-drill holes and 9 diamond-drill holes, totaling 3,535 feet of bore, at the Blewett zinc-lead deposit in Jo Daviess County, Ill. Attention of the Bureau of Mines was first directed to this deposit by the Illinois State Geological Survey, which had investigated the Blewett mine. In the opinion of the Survey and the Bureau of Mines, the record of production and results of drilling previously done on the property were considered sufficient justification for continuing investigation to the north and south along a projection of the trend. This report describes the work done by the Bureau on this, property and presents the data obtained.

Jan 1, 1948

By J. A. Domenico

A safe and precise mineral separation alternative to heavy liquids is being used for mineral sands exploration on large scale orebodies. The separation process, Magstream®, uses ferro-fluids and magnetic and centrifugal forces to produce precise split points over a range of specific gravities from 1.5 to 18.0 g/cc. This paper describes a commercial scale exploration program treating, roughly, 90 samples per day in Senegal (West Africa). Separation results comparing Magstream® and conventional heavy-liquid separation are presented.

Jan 1, 1994

By R Whittering, C Greet

High chrome grinding media has been used in the mining industry for quite some time, as it often proves economical on a wear basis. However, it is unusual for an operation to change to high chrome solely due to its metallurgical benefits. KagaraÆs Mount Garnet operation made the change from forged steel to high chrome media after laboratory testwork indicated that copper grades and recoveries would improve. The outcome was remarkable with positive changes in pulp chemistry throughout the circuit accompanied by marked improvements in copper, lead and zinc grades and recoveries. Reagent dosage rates were reduced, often by more than half, and the grinding media wear rate dropped to less than a third of the wear rate of the forged steel media. The economic analysis showed that out of the total increase of revenue and savings from metallurgical improvements and reagent and media consumption reductions the metallurgical improvements made up approximately 73 per cent, the reduced reagents saved 25 per cent and the savings through reduced media wear contributing by just over one per cent. This indicates that the popular view of high chrome media only being trialled in the plant for wear economics is outdated and the focus of operations should be shifted to using high chrome media for the metallurgical benefits.

Jan 1, 2006

By P Jackson, J Rea, M D. Goodz

The Morning Star Gold Mine has operated over a 101-year period, producing gold from narrow quartz veins and sulfide stockworks hosted mainly within a dioritic-gabbroic dyke. The deposit has been developed over a vertical depth of 980 m with drilling extending the vertical depth to greater than 1200 m. Currently there is a total Inferred Resource of 4.6 million tonnes at a grade of 6 g/t for 910 000 ounces of contained gold resources, which comprises an underground project and a surface project. Significant variation exists between the grade of drill core intersections and that observed in face sampling and subsequent production reconciliation (250 - 650 per cent). Studies were carried out on ten major production reefs, where the grades of drill intercepts were compared with face samples collected during development and mining. The implications of this study have been used as justification to assign production or stope/development grades where applicable to resources that are direct extensions of the historical development headings. Grade assignment and its impact on sensitivity for gold resources are detailed and show a 40 per cent variation in the gold resource, depending upon whether a production or calculated stope grade is used in grade assignment for the major reef deposits. Recent diamond drilling has intersected approximately 40 new gold bearing quartz reefs and sulfide zones that contain all the key mineralogical and structural indicators, and traditional large variations in gold grades similar to the historical major production zones. The implications of grade factoring and grade assignment are the greatest challenges confronting the resource estimation team in defining grade for these new zones. Grade assignment is seen as a method of balancing known historical production observations with the irregular grade distribution inferred from drill core assay results. Ongoing mine development and bulk sampling works are planned to validate the grade assignment process. The first stage of this process is the trial mining of the newly discovered Maxwell Reef (MR). The stope drawpoints were completed in August 2008 and the MRS1 stope is scheduled for completion in September. The stope reconciliation results will be presented at the October 2008 conference.

Jan 1, 2008

By John L. Lamont, Walter Crafts

SELECTION of an alloy steel for a heat-treated article has been facilitated by methods for the calculation of hardenability,1 as-quenched hardness,2,3 and tempered tensile strength.4 Ductility and toughness may also be estimated if the steel is completely hardened on quenching,5,6 and the present study was carried out in order to develop a basis for estimating the Izod impact strength of partially hardened steel. The investigation was directed toward the prediction of Izod impact strength in steels of normal commercial quality without consideration of special compositions or heat-treatments that might produce abnormal brittleness. It was found that Izod impact strength of alloy steel is controlled by hardness, degree of hardening on quenching, and grain size. In fine-grained steels the impact strength for any given degree of hardening is inversely proportional to the tempered Rockwell C hardness, and the relation of impact strength to hardness is lowered by incomplete hardening. Calculation of the tensile strength and impact strength of heat-treating steels has shown that, except at very high strengths, tensile strength is raised by alloys without loss of impact strength whereas the tensile strength gained by higher carbon contents tends to be accompanied by a disproportionate loss of toughness. Plain carbon steels give relatively low and unpredictable impact strength. The calculation is sufficiently accurate to be helpful in the selection of alloy steel, and common grades of alloy steel have been evaluated with respect to combinations of tensile strength and impact strength attainable after heat-treatment in sections from I to 4 in. in diameter. PROCEDURE The study of the relation of hardness to impact strength was based on test data derived from 24 heats from four producers. The steels included the following SAE and AISI compositions: 1020, 1o30, 1040, 1340, 3310, 3316, 4320, 4330, 4340, 8620, 8630, 8640, 8720, 8730, 8740, 9310, 9317, 9440, 9917 and three high-alloy chromium-nickel-molybdenum steels. As far as is known, the steels tested were of normal commercial quality. They were supplied in 4-in. sections, which were forged to smaller sizes, prenormalized, and machined to final dimensions. Heat-treatment was carried out by heating to the usual austenitizing temperature for the grade of steel, holding for one hour per inch of thickness and quenching in still oil at room temperature. Previous work had indicated that this quenching treatment approximates a severity of H = 0.35. The bars were tempered as follows: ½ in., I in., and I 5/8 in., 2 hr; 2 ½ in., 3 hr; 4 in., 5 hr. All bars were air-cooled from the tempering tem-

Jan 1, 1947

By Sue Xue, Carl C. Nesbitt

A project was completed which investigated the efficacy of recycling lead or lead monoxide from various fire assay wastes including crucibles, cupels and slag. The scope of the project was to determine optimal hydrometallurgical parameters so that direct separation and recovery of lead salts was economically feasible. A process was developed from the study which could use either acetic acid or nitric acid as a leachant, followed by several precipitation processes which could directly recover litharge (PbO) or other lead salts, such as lead carbonate or lead sulfate. The economics of the process is discussed. Analytical equipment such as the atomic absorption spectrophotometer and x-ray diffractometer supplied much of the information required for the study. However some novel analytical approaches using these instruments had to be developed to help in the determination of leaching kinetics and process quality control which are discussed.

Jan 1, 1999

By W. Crafts, J. L. Lamont

Selection of an alloy steel for a heat-treated article has been facilitated by methods for the calculation of harden-ability,' as-quenched hardness and tempered tensile strength.2 Ductility and toughness may also be estimated if the steel is completely hardened on quenching, 5,6 and the present study was carried out in order to develop a basis for estimating the Izod impact strength of partially hardened steel. The investigation was directed toward the prediction of Izod impact strength in steels of normal commercial quality without consideration of special compositions or heat-treatments that might produce abnormal brittleness. It was found that Izod impact strength of alloy steel is controlled by hardness, degree of hardening on quenching, and grain size. In finegrained steels the impact strength for any given degree of hardening is inversely proportional to the tempered Rockwell C hardness, and the relation of impact strength to hardness is lowered by incomplete hardening. Calculation of the tensile strength and impact strength of heat-treating steels has shown that, except at very high strengths, tensile strength is raised by alloys without loss of impact strength whereas the tensile strength gained by higher carbon contents tends to be accom- panied by a disproportionate loss of toughness. Plain carbon steels give relatively low and unpredictable impact strength. The calculation is sufficiently accurate to be helpful in the selection of alloy steel, and common grades of alloy steel have been evaluated with respect to combinations of tensile strength and impact strength attainable after heat-treatment in sections from I to. 4 in. in diameter. Procedure The study of the relation of hardness to impact strength was based on test data derived from 24 heats from four producers. The steels included the following SAE and AISI compositions: 1020, 1030, 1040, 1340, 3310, 33167 4320, 43.30, 4340, 8620, 8630, 8640, 8720, 8730, 8740, 931°, 9317, 9440, 9917 and three high-alloy chromium-nickel-molybdenum steels. As far as is known, the steels tested were of normal commercial quality. They were supplied in 4-in. sections, which were forged to smaller sizes, prenormalized, and machined to final dimensions. Heat-treatment was carried out by heating to the usual austenitizing temperature for the grade of steel, holding for one hour per inch of thickness and quenching in still oil at room temperature. Previous work had indicated that this quenching treatment approximates a severity of H = 0.3; The bars were tempered as follows: 34 in., I in., and 1% in., 2 hr; 235 in., 3 hr; 4 in., ; hr. All bars were air-cooled from the tempering tem-

Jan 1, 1948

By J. L. Lamont, W. Crafts

Selection of an alloy steel for a heat-treated article has been facilitated by methods for the calculation of harden-ability,' as-quenched hardness and tempered tensile strength.2 Ductility and toughness may also be estimated if the steel is completely hardened on quenching, 5,6 and the present study was carried out in order to develop a basis for estimating the Izod impact strength of partially hardened steel. The investigation was directed toward the prediction of Izod impact strength in steels of normal commercial quality without consideration of special compositions or heat-treatments that might produce abnormal brittleness. It was found that Izod impact strength of alloy steel is controlled by hardness, degree of hardening on quenching, and grain size. In finegrained steels the impact strength for any given degree of hardening is inversely proportional to the tempered Rockwell C hardness, and the relation of impact strength to hardness is lowered by incomplete hardening. Calculation of the tensile strength and impact strength of heat-treating steels has shown that, except at very high strengths, tensile strength is raised by alloys without loss of impact strength whereas the tensile strength gained by higher carbon contents tends to be accom- panied by a disproportionate loss of toughness. Plain carbon steels give relatively low and unpredictable impact strength. The calculation is sufficiently accurate to be helpful in the selection of alloy steel, and common grades of alloy steel have been evaluated with respect to combinations of tensile strength and impact strength attainable after heat-treatment in sections from I to. 4 in. in diameter. Procedure The study of the relation of hardness to impact strength was based on test data derived from 24 heats from four producers. The steels included the following SAE and AISI compositions: 1020, 1030, 1040, 1340, 3310, 33167 4320, 43.30, 4340, 8620, 8630, 8640, 8720, 8730, 8740, 931°, 9317, 9440, 9917 and three high-alloy chromium-nickel-molybdenum steels. As far as is known, the steels tested were of normal commercial quality. They were supplied in 4-in. sections, which were forged to smaller sizes, prenormalized, and machined to final dimensions. Heat-treatment was carried out by heating to the usual austenitizing temperature for the grade of steel, holding for one hour per inch of thickness and quenching in still oil at room temperature. Previous work had indicated that this quenching treatment approximates a severity of H = 0.3; The bars were tempered as follows: 34 in., I in., and 1% in., 2 hr; 235 in., 3 hr; 4 in., ; hr. All bars were air-cooled from the tempering tem-

Jan 1, 1948

By A H. Bagherieh, S Mesroghli, H Jorjani, S Chehreh Chelgani

The rare earth elements (REEs) assay and recovery in leaching processes is being determined using expensive analytical methods, ICP-AES, and ICP-MS. This paper presents a neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, neodymium recovery in the leaching of apatite concentrate. The effects of leaching times: ten to 40 min, pulp densities: 30 to 50 per cent, acid concentrations: 20 to 60 per cent and agitation rates: 100 to 200 rpm were investigated and optimised on REEs recovery in laboratory at a leaching temperature of 60¦C. The obtained data, on the laboratory optimisation process were used for training and testing of a neural network. A feed-forward artificial neural network with 4-5-5-1 arrangement, was capable of estimating the REEs leaching recovery. Neural network predicted values were in good agreement with the experimental results. The correlations of R = 1 in training stages, and R =  0.971, 0.952, 0.985 and 0.98 in testing stages were results for Ce, Nd, La and Y recovery predictions respectively and that theses values are considerably acceptable. It was shown that the proposed neural network model accurately reproduces all the effects of operation variables, and can be used in the simulation of a REEs leaching plant.

Jan 1, 2008

By Claudio Rocha Rosales

"Peñoles is a mining group with integrated operations in the smelting and refining of non-ferrous metals, and is also a chemicals producer. Peñoles is the world’s foremost producer of refined silver, metallic bismuth and sodium sulphate and is the leading Latin American producer of refined gold, lead and zinc. The Met-Mex Peñoles Zinc Plant commenced operations in 1973 with an annual production capacity of 105,000 t/y. Year after year the production has been increased, and at present, the production capacity is 240,000 t/y. In this paper, the leaching process,particularly the operation of the jarosite circuit is reviewed ,specifying process improvements to treat high iron calcines.INTRODUCTIONThe purpose of the leaching process is to recover the metals, mainly zinc,through a series of extraction stages with sulphuric acid solutions, which progressively increase the zinc recovery. After the series of acidification stages,the solution, which is rich in iron, is sent to the jarosite circuit to separate the zinc from the iron (Garcia & Valdez, 1996).The first step of the leaching process is the neutral leach circuit which produces a zinc sulphate solution that is sent to the purification section for the removal of impurities such as cadmium, cobalt and copper, after this solution is sent to the tankhouse to feed the electrolytic cells."

Jan 1, 2016

By S. Kelebek, U. Demir, T. C. H. Richards, E. Koss

"Laboratory-scale tests were carried out to investigate the response of a high-grade (~143 g/tonne) well-liberated gold ore to flotation using two collector types. Octyl and amyl xanthates, representing conventional types of collectors, were tested against an n-octanoic and hexanoic acids under moderate and high redox potential conditions. The latter was based upon a suggestion in literature that monocarboxylic acids are able to adsorb onto the surface of gold at redox potentials near 600 mV (SCE). This investigation did not demonstrate that these carboxylic acids could function as collectors for gold in real ores. In fact, they appear to have slightly depressed gold. However, the results demonstrated that octyl and amyl xanthates acted as highly effective gold collectors for this ore and that an increase in the collector dosage led to an increase in recovery for all mean particle sizes. In some tests, gold recoveries of around 95% were attainable in concentrates with grades around 6 kg/tonne, indicating that xanthate flotation remains a viable means of concentrating gold even at coarse grain sizes. Various aspects of the process such as grade-recovery performance and recovery by size are discussed.INTRODUCTION Three methods are used for the recovery of gold in mineral processing, either alone or in combination: gravity concentration, cyanidation and flotation. Gold occurs as a by-product in some ores together with platinum group metals and as the primary metal in other ores in the form of native gold and electrum, which are alloys of gold, silver and minor amounts of copper. Flotation is a viable method for recovering liberated gold where the gold is visible under an optical microscope (greater than 1 µm in size) and where the attachment of gold grains is not prevented due to bubble loading by competing minerals. It is generally known that grains finer than 150 µm in size will float with most collectors."

Jan 1, 2017

By W. J. Sharwood

Cupellation is well known to be one of the most effective methods of separating silver and gold from base metals and other impurities, as well as one of the most accurate means for their estimation. In the latter application it consists in absorbing in some porous medium the fused lead oxide formed by the oxidation of the lead "bath," which carries with it the oxides of other base metals present. It has long been recognized that small amounts of both silver and gold were removed and absorbed together with the base metals, as well as being to some slight extent volatilized, and in work of the highest accuracy a correction is made for the "cupellation loss." Thus in the assay of bullion this is done by means of "proofs" of like composition, which are manipulated throughout in precisely the same manner as the assay pieces, and are assumed to lose or gain like amounts. In the case of certain very rich ores and commercial products the loss is adjusted by assaying the cupel itself and recovering the precious metal absorbed, but this doubles the labor and does not remedy the loss by volatilization. Arbitrary tables have been drawn up by various authorities with the object of enabling a correction to be applied without the use of a check. These have been of very limited practical use owing to the fact that a number of factors affect the losses sustained. For a fixed amount of precious metal the loss varies with the amount of lead used, with the nature and amount of the impurities, with the porosity of the cupel, with the air supply, and above all with the temperature at which cupellation is carried on. Pure silver loses relatively much more than gold, but the loss in either is diminished by an addition of the other metal. The concentration of precious metal in the litharge increases as the concentration in the lead increases, but little work has been published connccting the two. If all other conditions remain the same the actual total loss increases, but the percentage loss diminishes, with an increase in the weight of precious metal treated. The results of an immense number of experiments have been published at various times- during the past hundred years giving the actual or the percentage losses suffered under various conditions of cupellation, but the data are widely scattered and few attempts have been made to correlate them, so that no definite law has heretofore been shown to exist

Jan 1, 1916

By R. Patrick

As a unique South African organisation, CSIR: Division of Mining Technology (Miningtek) strives to support the mining industry by improving health, safety and productivity through developing, adapting and transferring technology. Considerable effort is currently directed towards the development of potential non-explosive mining methods with the potential to allow continuous mining in narrow reef conditions. Besides improving productivity, continuous mining results in concentrated mining which has a significant impact on reducing infrastructural costs. Impact Ripping and Water Pulse Rock Breaking have been tried on gold mines, whereas Activation, Mini-Disc? cutting and the Plasma Holemaker are currently being tested on platinum mines. The organisation?s many years of experience in novel rockbreaking, together with its world-wide collaborator network, has placed it in a unique position to assist the mining industry and manufacturers in developing and/or adapting existing technologies for application underground. Currently a range of technologies are being investigated, which have reached different stages of maturity. The main technologies under investigation are; - Impact ripper system - Water pulse rock breaking - Activated undercutting rollers - Mini disc cutters - Electric rock breaking

Oct 1, 2001

The 8 ft by 91/2 ft drive which joined No. 7 Shaft with Browne Shaft on the 1,480 ft level was extended from both ends and met at a point approximately 12,000 ft from No. 7 (2,000 ft from Browne).The surveying required for this 2 1/2 mile haulage drive called for greater accuracy than was obtainable from South Mine standard methods. Procedures and devices from published information were tried and modified as required to suit local conditions. Several new methods were applied and improved as the drive advanced. The control of angular, linear and level measurements was perhaps considerably in excess of the requirements, but this was offset by abnormally large discrepancies resulting from shaft plumbing. The accuracy of the final breakthrough, although not to the standard desired, was sufficient to complete the connection without inconvenience and added cost.INTRODUCTIONThe acquisition of the Browne Shaft leases in January 1962 presented the management of Broken Hill South Limited with the problem of transporting ore from these leases to its mill. It was eventually decided that diesel locomotivehaulage through a 2t mile drive on the 1,480 ft level between the two mines was the best solution. The drive was advanced from both ends after Browne Shaft was deepened by 80 ft to reach the 1,480 ft level horizon. Each end advancedabout 15 ft/day with the miners working three 7 hr shifts. Blasting was restricted to the end of the shift.The survey work involved five shaft plumbings and 78 theodolite stations in a traverse, underground and surface,of more than 5 miles. Because of the exceptional length of the drive, an unusually high degree of reliability was required.The aim was for a maximum error at breakthrough of 1 ft 1 in 30,000, and to secure this, precise methods of linear measurement were necessary. Shaft plumbing in particular posed special difficulties.

Jan 1, 1965

By Conné Spangenberg

Contents ?Introduction ?Metal accounting environment ?Problem statement ?Investigations & Achievements ?Metal Accounting ?Principles ?Standards ?Audits ?Questions

Jan 1, 2005

By Zbigniew Lubosik, Andrzej Walentek, Stanislaw Prusek, Sylwester Rajwa, Aleksander Wrana

"Underground coal gasification (UCG) provides a solution to supply electricity from high ash coal or deep deposited seams. The coal is consumed in situ, and, accordingly, the ash is left underground. UCG could play a major role in the future of coal, which is expected to fuel 44% of the world’s energy in 2030, in a more environmentally friendly and commercially viable manner. Nevertheless, it is known that the UCG can impact the environment. One of the most important factors in safe UCG process should be the evaluation of rock mass quality and the monitoring of its behaviour. The changes of rock mass parameters and quality have an influence on numerous aspects, such as subsidence and the stability of underground workings in georeactor vicinity, however, they also increase the possibility of pollutant migration through fractures and pores. These issues are especially important in cases of gasification conducted in an operating mine or on areas of high ecological vulnerability. This paper details observations made in two underground trials of UCG performed in Poland recently. The first of which is the Experimental Mine Barbara (under the project entitled HUGE-2 Hydrogen oriented underground coal gasification for Europe – Environmental and Safety aspects, (Wiatowski et al., 2015). The other trial has been conducted at an operating mine, Wieczorek, which is in the framework of a research project on the development of coal gasification technology for highly efficient fuel and electricity production (Czaplicka-Kolarz et al., 2013). During these trials, investigations were carried out aimed at assessing geomechanical parameters of rock mass and support behaviour in surroundings of UCG geaoreactors. Investigation comprises assessment of geomechanical parameters of coal, floor and roof strata, roof displacements, and concrete support strength parameters variation, as well as standing steel support load. Hydraulic penetrometer, endoscopic camera, Schmidt hammer, pull-out method, telltale, and ground penetration radar (GPR) were used in the investigation. Research conducted at both EM Barbara and Wieczorek Collieries revealed that the UCG process did not adversely affected the competency of rock mass (expressed by number of fissures and strength parameters of rocks), the stability of roadways and the support performance in the areas located in the vicinity of the georeactors."

Jan 1, 2017

By J R. Manuel, J M. F Clout

The importance of goethite to Australian iron ore production is steadily increasing as the proportion of goethite-rich, martite-goethite bedded and channel iron deposits increases at the expense of declining production from high-grade microplaty hematite deposits. For this reason, an improved understanding of goethite in iron deposits, its genesis, goethite types and their physical and metallurgical properties is vital to maintaining optimum sintering and blast furnace performance in Asian steel mills.The terminology used to describe goethite in Australian iron deposits is currently highly variable. The discredited mineral name ‘limonite’ is still in widespread use as a field term for goethite and there are many misconceptions concerning goethite chemical grade and downstream physical and metallurgical properties. The goethite classification proposed here is based on geological and physical properties from which three types are recognised including brown goethite, dark brown-black vitreous goethite and highly microporous, friable yellow ochreous goethite.In practice, typical vitreous goethite with highly reflective surfaces and conchoidal fracturing, characteristic of the hard cap zone appears from X-ray fluorescence (XRF) and electron microprobe analysis to be significantly higher in Si (up to 18.7 wt per cent), Al (up to 3.5 wt per cent) and S (up to 0.14 wt per cent) compared to the generally very low (<1 wt per cent for Si and Al) levels of these elements in ochreous goethite and brown goethite. The data dispels the common misconception that friable earthy or yellow ochreous goethite is high in Al and Si and other chemical impurities. However, P was found to be consistently higher (mean of 0.112 wt per cent and up to 0.296 wt per cent) in ochreous goethite than brown goethite (mean of 0.011 wt per cent) or vitreous goethite (mean of 0.031 wt per cent). The highly porous microstructure of ochreous goethite is thought to have a much higher surface area, which may aid in preferential adsorption of P onto the ochreous goethite mineral surface.CITATION:Manuel, J R and Clout, J M F, 2017. Goethite classification, distribution and properties with reference to Australian iron deposits, in Proceedings Iron Ore 2017, pp 567–574 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017