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By D Garcés, M Meléndez, R Castro, E Viera

Enhancing the understanding of gravity flow in caving operations is a key factor in the design, operation and success of caving methods. Consequently, much research has been performed to increase knowledge about gravity flow. Many valuable theories have been gained from different research approaches, which include physical modelling, numerical modelling and a limited number of full-scale tests. Recent advances in technology have allowed Codelco Chile to carry out trials using Smart Markers technology. This technology was used in Esmeralda mine’s Block-2 at El Teniente mine from August 2012 to January 2015. This paper aims to determine the characteristics of the extraction zone and obtain the data that will allow greater understanding of gravity flow for design and draw control purposes.The collected data from recovered markers were analysed using a linear interpolation of both the initial position of the markers and drawbell accumulated drawn tonnage. For each drawpoint in the trial, the regularity or irregularity of flow was analysed based on the recovered markers and the drawn tonnage. Correspondingly, the relationship between flow characteristics and observed fragmentation in drawpoints was analysed. The gravity flow of the Smart Markers revealed that current drawpoint spacing provides the interaction conditions of adjacent flow zones. However, it is possible to increase the drawpoint spacing while allowing caved rock to be extracted from the major and minor apexes.The results of this research also verified that full-scale test data are the predominant factor in the production level design and production control at El Teniente mine.CITATION:Garcés, D, Viera, E, Castro, R and Meléndez, M, 2016. Gravity flow full-scale tests at Esmeralda Mine’s Block-2, El Teniente, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 349–358 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Marcus A. Wiley, Gregory Abramov

Borehole mining (BHM) is a remotely operated method of extracting rock material through boreholes by high-pressure water jets. Figure 1 illustrates a BHM tool and fluids circulation. The tool consists of at least two pipes, one for pumping down high-pressure water, the second for delivering slurry to the surface. This article reviews the BHM process. It discusses current and new applications for borehole mining and help the readers determine if BHM is applicable in their situations. Previous articles in ME about BHM explained either a particular project (ME, April 2001, pp. 33-36) or a newest patent in this area (ME, March 1991, pp. 313-318). However, neither one provided an overview on the modern BHM technology.

Jan 1, 2004

By Pablo Velasco

The Belize economy recorded modest growth during 1980; the growth of the gross domestic product (GDP) in real terms was between 1% and 2%. At current prices, the 1980 GDP reached $108 million2. This output was largely attributed to the performance of a few industries, mostly nonminerals. Such performance improved significantly the balance of payments situation by reducing the deficit from $19 million in 1979 to $4 million in 1980. The rate of inflation was an estimated 18% in 1980 and would have been greater if not for a conservative monetary policy and price control on a number of essential items. Expert earnings increased $43 million, or 50%, from the 1979 level. After increasing more than 25% in 1979, imports increased only 6% in 1980 to a level of $141 million owing to the decline in investment and stabilization of petroleum prices. The balance of trade deficit was $9.8 million in 1980, a marked improvement from the 1979 level of $45.1 million. The mineral output for Belize accounted for only a fraction of 1% of the GDP. Such activity was limited to the production of limestone, marl, and sand and gravel, all of which were primarily used in construction of the Northern Highway between Orangewalk and Belize City. Mineral resources are deficient or nonexistent in Belize for the majority of metals and nonmetals, although the Government and others continue to believe that petroleum must exist in Belize. The proximity to Mexican oilfields and the growing finds in the Peters area of Guatemala support this expectation. The Government continues encouraging exploration onshore and offshore and offers terms that

Jan 1, 1982

By M. Potesser

One of the main targets in the automotive mass industry and supplying industry is the weight reduction of the vehicle for decrease of the fuel consumption. For that reason combinations of different kinds of materials and connections of, for example, steel and aluminium are developed or are already successfully field-tested. A determining factor concerning the quality assessment of the welded joint during hybrid welding is the characterization of the intermetallic Fe-Al layer regarding strength, hardness, morphology and mainly the different phases in which Fe occurs together with the Aluminum (FeAl, Fe2Al5, FeAl3.). A combination of conventional light microscopy, SEM - EDX - analysis, the usage of an atomic force microscope including a Nanoindenter and theoretical thermodynamic calculations turned out to be highly effective. Based on the attained results, the constitution of the intermetallic FeAl layer, influenced by silicon, manganese and zinc, can be predicted.

Jan 1, 2006

High Pressure Sulfuric Acid/Oxygen Leaching of Platinum Group Metals Bearing Ni-Cu Mattes The processing of platinum bearing Ni-Cu ores for the extraction of platinum group metals (PGMs) involves comminution, flotation, smelting, and converter treatment of the furnace matte. Leaching circuits are predominantly used for further processing to separate the base metals and PGMs contained in the converter matte. Nickel dissolution is primarily achieved in the first stage leach (high pressure or atmospheric leaching, or a combination of the two), which is followed by second stage high pressure sulphuric acid/oxygen leaching to dissolve copper and the remaining nickel. PGMs are recovered from the leaching residue in downstream processes, and their dissolution in the first two leaching stages must hence be limited. Studies have been conducted to investigate the leaching mechanisms and kinetics of base metals in different leaching environments. The key operating parameters that influence the leaching kinetics of these metals include the temperature, acid concentration, degree of agitation, feed particle size distribution, and oxygen partial pressure. There is, however, a limited understanding of the behaviour of PGMs in the high pressure leaching process. Consequently, this process is controlled based on operators' intuition despite its importance in the recovery of PGMs. An improved fundamental understanding of the behaviour of PGMs in this leaching environment is required to be able to accurately model the process. This in turn will allow the development of an improved control strategy and the estimation of optimum operating conditions. An overview of the leaching mechanisms of base metals and the effects of key operating parameters on their dissolution kinetics in different leaching environments are presented. Models that have been developed to predict the leaching behaviour of base metals are discussed and evaluated. Finally, initial results obtained with an experimental setup that will be used to investigate the behaviour of PGMs in high pressure leaching systems are discussed and compared with published results.

Sep 13, 2010

By N. W. Kirshenbaum

"The Marconaflo slurry system was originally developed to reduce costs and solve technical problems in the marine transport of mineral cargoes. In the short time since its inception, it has been found to offer economies and advantages for land-based and in-plant materials handling. This efficient method of reclaiming and slurrying particulate materials at very high pulp densities can be directly utilized in a wide variety of mineral process systems. These include: storage-reclaim applications, where even cohesive, compacted materials can be reclaimed from settled storage ""on demand""; the growing number of hydrometallurgical operations wherein slurried materials are processed to extract or yield metals; certain applications associated with pyrometallurgical treatment; and as a means of augmenting the performance of conventional mineral dressing equipment, such as thickeners.INTRODUCTIONIn the continuing effort to lower costs of producing minerals and extracting metals, the field of handling and transportation often receives too little attention from those engaged in the mining and winning of ores and metals. This comment, which pertains to ferrous and non-ferrous as well as to non-metallic producers, is especially pertinent to products having relatively low value, where transport costs can be a major portion of the delivered selling price to the minerals receiver.One method which was developed recently for the purpose of reducing costs and solving technical problems in marine transport and handling of mineral cargoes is the MARCONAFLO slurry system. A notable feature of this system is its versatility; in addition to its use in marine transport1*, some of its diverse applications have included the mining and reclaiming of tailings2 and in-plant materials handling3. As the concept and fundamentals of this system have been well explained previously4,5, the mechanics of the system will not be elaborated upon here. Rather some specific ways in which MARCONAFLO can be applied to processing and extraction will be explored."

Jan 1, 1973

By M D. Uttarwar, R R. Yerpude

India is the world’s third-largest producer of coal and is endowed with the fifth-largest coal reserves in the world. Surface mining straddles the entire domain of the Indian coal mining industry, yielding over 88 per cent of production. With continually rising domestic demands, it has to shoulder the responsibility of sustaining the requisite increase in coal production and chasing commensurate stripping targets. Such an ambitious task calls for the deployment of smart technologies. In such a demanding situation, cast blasting of overburden has emerged as a promising alternative for enhancing production and productivity of dragline pits.The cast blasting technique reduces stripping costs significantly as it utilises the chemical energy of explosives in place of mechanical energy to move large volumes of overburden quickly. Proper application of cast blasting not only reduces overall mining costs but also increases coal production. This paper investigates and evaluates the potential of the cast blasting technique, with special reference to dragline pits employing the rehandle method of extended bench. The economic feasibility of the technique is also ensured under different scenarios so that considerable benefits would accrue to the individual surface coalmines. To underline the efficacy of the technique, different cast blasting models have been formulated under a range of operational and economic scenarios that resemble present day practices in India. In order to test for economic variability in the application of the technique, a risk analysis of all the formulated cast blasting models is performed using net present value.CITATION:Uttarwar, M D and Yerpude, R R, 2015. Potential of the overburden cast blasting technique in Indian surface coalmines – a modular approach and its financial implications, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 655–664 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By L. J. Prosser, A. T. Iannacchione

Unfortunately from 1991 through 1995, 44 miners were fatally injured in the stone industry. Of these 12 occurred at underground mines from a total work force of less than 2,000 miners. Nine of these 12 miners were fatally injured in falls of roof or rib. A safer environment for the miners can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground control strategies. Roof and rib conditions in the underground stone industry were observed and assessed at 33 mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania, and West Virginia [(Figure 1)]. Hazard assessment indicated that those ground failures occurring under moderate to substantial overburden (> 30 m [l00 ft]) were caused by stress concentrations and geologic structures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine layout decisions tremendously influence ground stability.

Feb 24, 1997

Stope back conditions in the cut-and-fill stopes at New Broken Hill Consolidated Limited often deteriorate to such an extent that, because conventional rockbolts are not able to maintain safe working conditions, square-set timber is installed. An attempt to eliminate this costly procedure has involved the use of long grouted rockbolts using high tensile prestressing wire. These bolts were developed in conjunction with the prestressing engineers of BBR (Aust.). This form of support has improved the back conditions, maintained safe working conditions, and delayed the introduction of timber in a number of stopes.Production from these stopes has been maintained at its previous level (at a rate approximately double that of a comparable timber stope).

Jan 1, 1974

By R E. Gerald II, B Zhang, T Sander, J D. Smith, J Huang, R J. O’Malley, H Tekle

In the steelmaking process, mold fluxes are essential for ensuring thermal insulation, refining, and the efficiency of continuous casting. Real-time understanding of the in-service composition of slags and fluxes are crucial for optimising the steel production process and improving the quality of the final product. An in situ fibre-optic Raman probe that enables the study of the structure, composition, and viscosity of molten slags and fluxes at steelmaking temperatures has been developed and demonstrated both in the lab and in foundry scale experiments. The focus of this study is on the structural, compositional, and property analysis of molten fluxes in a laboratory setting, with the aim of applying this technology for in situ monitoring during industrial production. Raman spectra were successfully collected at various temperatures from 1000°C to 1400°C in real-time and analysed using a deconvolution algorithm to isolate and quantify peaks in the spectra associated with the specific structures of molecular components in molten and solidifying flux. The research successfully combines in situ Raman spectroscopy with high-temperature viscosity data, specifically targeting CaO-CaF-SiO2-Al2O3 based mould flux systems. Specified ratios of the deconvoluted Raman peaks, such as Al-O-Al/Si-O-Si ratio, shows good correlation with the flux chemistry, while the Q3/Q0 peak ratio shows good correlation with viscosity. A ruggedised Raman probe system was also developed and demonstrated in an 80 kg induction furnace. Ultimately, the goal of this work is to demonstrate in situ slag and mould flux analysis in industrial processes, such as in the continuous caster or electric arc furnace (EAF).

Aug 21, 2024

By G Chitombo, D Francis, P C. Stewart, I Brunton

The ability to precondition (weaken) a rock mass to enhance caving (cavability and fragmentation) is becoming increasingly important, as more potential caving deposits are in stronger rock masses, and at greater depth. This paper discusses a full-scale blast preconditioning experiment conducted at the Cadia East mining operation, including quantification of visible and microscale blast damage. From a cave mining perspective, the objectives of the experiment were to quantify the effect of confined blasting on rock mass characteristics relevant to enhanced caving, and to provide calibration data for the purpose of numerically modelling alternative blast preconditioning designs.The experiment was located approximately 360 m below surface, and consisted of two f165 mm blastholes (60 m vertical holes) and eight HQ diamond drill monitoring holes (35 m horizontal holes). The diamond drill holes were used to sample the rock mass before and after the blast at varying distances from the blastholes. Rock mass blast damage was quantified both visually using core logging, and on a microscale using LABYRINTH® statistical analysis of X-ray microtomography data. Results from the experiment indicated four major findings:on the visible scale, the experiment indicated a 147 per cent increase in the number of hairline cracks within 5 m (p value = 0.015), but no change in geotechnical logging parametersmicroscale tomography of intact rock samples indicate significant localised intact rock damage up to 4 m from the blasthole (p = 0.007)preliminary point load test results indicate that blast damage results in a significant reduction in intact rock strength (p = 0.050)the significant increase in porosity and microfracture size associated with damage provides a mechanism for reduced intact rock strength due to confined blasting.CITATION:Stewart, P C, Brunton, I, Francis, D and Chitombo, G, 2016. Quantification of rock mass damage associated with a confined blast preconditioning experiment at the Cadia East block cave, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 119–132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Rodger C. Smith

The topic chat has been assigned to me ?Economic and Political Climate of the Potash Industry? is a function of two basic facts: 1. Potassium is absolutely essential to plant and animal growth. Along with nitrogen and phosphorus it is one of three major plant nutrients, the three nutrients required in largest quantities for plant growth. 2. United States is unequivocally an "have not" nation with regard to potassium. Quantity of potassium ores is limited and, more disturbing, the cost of production at all U.S. potash mines is marginal in comparison with the major producing countries, i.e. Canada and U.S.S.R.

Jan 1, 1983

By Collin L. Stewart

The high cost and limited flexibility of modern longwall systems has resulted in the need for mine engineers and geologists to predict possible adverse mining areas ahead of mining and to then design and implement suitable ground control solutions in a timely and cost effective manner. Therefore, over the last 30 years, geo-technical evaluations for coal mine planning and development have advanced from a minor afterthought to an important part of today?s successful, high capacity, longwall mining operations. The latest iteration in this progression of improved analysis for predicting future mining conditions is a computer-based Stability Mapping System developed by West Virginia University. This system is designed to allow the mining engineer and geologist to effectively combine the mine geologic characteristics, stress influences, and structural features into an integrated stability map for use in mine planning and support design. This paper details the application of the stability mapping system to Bowie Resources, LLC, Bowie No. 3, multiple-seam longwall coal mine. At this mine, the prediction of adverse mining conditions using the stability mapping system allowed management to accurately adjust their support densities and operational procedures, and to successfully mine through difficult conditions safely and successfully.

Jan 1, 2006

By K. Lundholm, A. E. Mäkinen

"Ore grades are declining and getting more complex around the world which not only complicate the ore processing but also produce new type of requirements to manage the produce waste streams. One specifically problematic and increasingly identified element in waste streams produced in mining and metallurgy is arsenic.Arsenic is a compound that has no significant market value, but that needs to be removed from ores, concentrates and other process streams because of environmental or process technical reasons. One example of a removal process is partial roasting of high-As sulfide concentrates, originally developed by Outotec. In this process the arsenic is volatilized in the gas phase and thus separated from the solid material, i.e. the calcine. If the arsenic is recovered by wet methods the process gas is quenched and all arsenic needs to be stabilized in the effluent treatment plant.Outotec has developed ferric arsenate precipitation as a method to produce stabile arsenic residues from wet gas cleaning effluents. Iron based precipitates, when correctly produced, can meet typical landfill criteria measured with different types of leaching methods meant for characterizing the arsenic dissolution behavior from the precipitates.In this paper partial roasting of sulfide concentrates with arsenic volatilization in combination with ferric arsenate precipitation is discussed from the perspective of producing wastes that can meet the stability requirements set by common leaching tests methods, TCLP and CEN. These leaching test methods set the normative landfill requirements for most operations generating arsenic containing wastes. A typical flow sheet of Outotec® Ferric arsenate process is discussed with results showing the importance of correct process control and sequence on producing arsenic containing waste that can meet the landfill disposal requirements."

Jan 1, 2014

By M. F. van der Merwe

Anglogold Ashanti?s Kopanang Gold Plant (previously No. 9 Gold Plant) treats ore from Kopanang and Tau Lekoa shafts. The plant is twin streamed and has dedicated treatment circuits, from milling to final product, for each shaft. Waste rock material is used to compensate for the mill gap on both streams. Each stream consists of three 4.85 m x9.15 m ROM mills in closed circuit with a single stage hydrocyclone, milling an average of 7 000 t per day. The liner configuration in each mill consists of six rows of 30 grid liners along with rectangular lifter bars. The topic of gold lock-up is not new and has been investigated and reported on many times, both within Anglogold Ashanti and the broader mining industry. Although the lock-up mechanism is understood, its measurement is neither practical nor precise. The initial lock-up in a new liner and the release as the liner wears down cannot be accurately quantified. Previous test work carried out on Kopanang Gold Plant (with a ?gold scanner?) measured the natural gamma radiation emitted by uranium. This radiation is in proportion to the mass of concentrate locked up in the grid liner pockets, as well as between the cast-on backing plate and the shell. The ratio of concentrate lock-up was estimated as 35% behind the liners and65% in the pockets. Mill gravity concentrates are recovered during routine relining operations from behind the grid liners at Kopanang Gold Plant. Prior to relining, the liners tend to release the concentrate from the pockets as the liners wear. Historical Kopanang data from actual ?mill gold? smelted indicates that an average of 29 kg gold is recovered from behind each row. This indicates a total lock-up of 250kg gold per mill. This locked-up gold should preferably be minimizedor eliminated for the following reasons: ?The cyclic build-up and release of gold in mills complicates accounting ?Gold concentrate arising from liners is a security risk and creates a major mechanism for gold theft ?Loss of interest on the value of 250 kg fine gold is significant and was a major driver for the project. These factors led to the need to develop techniques to eliminate or at least minimize the gold lock-up in the mills. Wave liners, with rubber inserts, have been successful in eliminating lock-up, and were tested at Kopanang Gold Plant in November 2000. However, due to increased load-slip and high wear rates associated with these liners, this option proved less economical in terms of liner wear. Grid liners, with rubber-filled pockets, demonstrated a very high wear life and eliminated pocket lock-up. This system was successfully trialed in January 2003, but unfortunately did not prevent lock-up behind the liners. Current developments have resulted in a system that eliminates both pocket and backing plate lock-up. The conventional grid liner design has been modified to remove its steel backing plate. Rubber inserts that are integrated onto a rubber backing plate, have been designed to be used with the newly modified grid. The backing plate and grid pockets are now completely occupied by rubber, thus completely eliminating concentrate build-up around the new grid liner system installed in November 2003. Results to date are promising and liner life is expected to exceed conventional performance.

Jan 1, 2005

By Gray Mullins

This paper presents results from model and full-scale tests to assess the interface bond between a cast-in-place concrete seal slab and steel H-piles in cofferdams. Three different seal slab placement conditions - fresh water, salt water and bentonite slurry - were evaluated and the results compared against controls where no fluid was displaced by the concrete. Normal pile surfaces were investigated. Additionally, the situation of ?soil caked? piles was also tested. In the model tests, eight 15 cm deep, W6 x 15 sections were used for two different embedment depths of 1.5d and 2d, d being the depth of the section. In the full-scale tests, 16 specimens 35 cm deep (W14 x 90 sections) were tested with the embedment varied between 0.5d-2d. The results show that significant bond stresses developed even in the worst placement condition. Recommendations made for revising current values in specifications have already been implemented by the Florida Department of Transportation.

Jan 1, 2013

Situated in the Greymouth Coalfield, the Mt Davy Block contains a significant resource of high quality bituminous coal suitable for use in metallurgical coking coal blends. The coal, which is all low sulphur, is seen as a complementary deposit to export coking coal at Stockton Mine.   Previous drilling by State Coal Mines (1948 - 1953) and Japanese interests (1970's) have been supplemented by Coal New Zealand drilling (1992 - 1993) and surface mapping. A mining feasibility study was completed in late 1993 and approval gained for the driveage of an exploratory tunnel to the target seam.   Following construction of surface facilities, tunnel driveage on a 1:5 decline commenced from Rewanui in May 1995 and to date about half the required length has been driven. When the seam is intersected a comprehensive geotechnical testing programme will be undertaken to assess the in-situ mining conditions. It is expected that the results will confirm the assumptions made in the feasibility study.   The Mt Davy Mine, at depths of 500 - 700 metres, will be the deepest underground coal mine ever inNew Zealand and in-situ stresses (orientation and magnitude) will be important considerations for mining engineering. The coal has a high gas content and suitable techniques for gas control and prevention/mitigation of coal outbursts will be necessary.   Mine development is scheduled to commence in mid 1998 and an annual production level of 500 000 tonnes is forecast. The coal seams will be developed by continuous miner and coal extraction will be by hydraulic monitor. Coal will be pumped to the surface and from Rewanui transported five kilometres to Dunollie either by truck or slurry pipeline. At Dunollie a coal dewatering plant, coal stockpile and rail loadout will be constructed.

Jan 1, 1996

By Steve Kral

The domestic mining industry may be in the doldrums but there appears to be hope, at least from a regulatory standpoint. At least one US senator believes that the events of Sept. 11, 2001 made many citizens see the need for the country to become more self-reliant on its growing energy needs. Even before that tragic day, however, the Bush administration was making a strong push to open up more public land for energy and natural resource development.

Jan 1, 2002

Geophysical anomalies result from the passage of hydrothermal fluids through rocks. Interpretation of these anomalies, when integrated with available geological and geochemical data, assists the construction of a conceptual model of the original hydrology of the system. The original extent of a geothermal system is often indicated by the distribution of low resistivity argillic clay alteration. Quartz-adularia vein deposits, silica sinters or stockwork (often mineralised) cause local increases in resistivity. Appropriately chosen electrical techniques can therefore be used to help target such structures. Airborne magnetic surveys have also proven useful in New Zealand epithermal exploration, because hydrothermal fluids destroy magnetite causing extensive demagnetisation anomalies. Ground magnetic surveys can sometimes be useful for geological interpretation on a local scale. Positive gravity anomalies may occur as a result of mineral precipitation (silica or calcite) in high porosity host rocks, while negative gravity anomalies can result from hydrothermal fracturing and leaching of relatively dense host rocks. The relative merits of these geophysical techniques as used in the exploration of epithermal mineral prospects are discussed, with particular reference to the Hauraki Goldfield. The preferred method for defining zones of quartz veining/silicification is vector or tensor gradient resistivity. Exploration strategies and technique refinements are suggested as a means of improving the resolution of potentially mineralised target structures, in a more efficient and cost effective manner.

Jan 1, 1993

Power Plant. The power for the metallurgical operations is supplied by the company's own power plant, which is centrally situated. Power is also supplied to Metal Manufactures Ltd. and Australian Fertilizers Ltd., both being adjacently situated to this company'sworks.The power supplied is direct current, 250 volts, and is obtained from direct-current generators coupled to turbines and to Belliss & Morcom triple expansion engines.The steam supply is obtained from Babcock & Wilcox water tubular boilers, the fuel used being drawn from the South Coast coal mines.Transport. - The works are connected by standard broad gauge railway to both the jetties and the Government railway. Two steam and three electric locomotives are employed in this service.In addition to its own requirements, transport is provided to Metal Manufactures Ltd. and Australian Fertilizers Ltd.The various operating departments are connected by a 2-ft. gauge railway operated by Jeffrey electric locomotives.Ore Storage and Sample Mill - These departments are connected by broad gauge line to the Government railway and jetties. All material which is railed or shipped to the works from the various centres is weighed, sampled and placed in the ore store, or outside gantries, before being treated.Since the whole of the material received is either purchased or treated on a toll charge, great care is necessary in the weighing and sampling of all the receipts.Assay Oflice--The assay office is divided into several laboratories, where analyses of the various purchased materials and works samples are carried out.

Jan 1, 1938