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By Claudio Toro, Alex Moyano, Jonkion Font, Carlos Caballero, Pedro Morales

"Codelco-Chile in the last decade has carried out industrially-oriented research as an alternative to the traditional batch-type converting process. In a first stage carried out preliminary evaluations in a rearranged Peirce Smith (PS) converter, and then an exploratory test in a “Convertidor Teniente” (Teniente converter, TC) for the Codelco-Chile Continuous Converting Process. However, the validation test for this process in the TC was delayed up to the second quarter of 2007 where the validation studies were done satisfactorily.Thus, the objective of this paper is to present the results of the campaign tests validating the Codelco-Chile Continuous Converting Process in the TC1 of the Codelco Norte smelter.The results of charging the solid or liquid matte or high grade matte (“white metal”) by Garrgun, or by mouth of the 22 m x 5 m TC1 are presented. Some features of the industrially validated process are discussed, and the pilot test results of the matte injection are also presented."

Jan 1, 2009

By Hubert Erik Sherer

Determination of the best time to replace an aging unit of equipment is a recurring problem which is common to essentially all surface and underground mining operations. Virtually all mining equipment is subject to wear and the resulting deterioration that increases with equipment life. This mechanical deterioration results in lower availability and, thus, decreasing, production. Due to decreasing production and increasing repair costs, there is an optimum age at which the replacement of a given equipment unit with a new unit will result in the lowest cost per unit of production for the equipment operation in question (Figure 1). Determination of this optimum replacement age is further complicated by factors such as: possible overhaul alternatives, fleet replacement and expansion alternatives, remaining life of the mine, and technological improvements in the potential replacement or differences in the production capacities of these replacements. Determination of the optimum time to replace an equipment unit becomes more critical each successive year due to the rising capital costs of new equipment versus maintaining old equipment. An incorrect choice of the replacement age for an equipment unit can result in excessive costs to the mining operation. If a unit is replaced too early, the capital cost of the unit is not fully utilized; conversely, replacing a unit too late results in excessive maintenance costs and low production. The economic life of a piece of equipment is the equipment age that results in the lowest total discounted cost per unit of production for that piece of equipment, not considering the cost of future replacements. The economic life of a piece of equipment is usually shorter than the physical life, the maximum age at which a machine is capable of doing useful work. The optimum replacement age for a piece of mining equipment may vary from the economic life of that equipment due to the remaining life of the mine, fleet considerations, costs associated with potential replacement machines, and capital rationing constraints. For example, the equipment life of the current machine that may result in the lowest cost per unit of production might be 10 years; however, when the timing of the future replacement costs are entered into the calculation, a different life for the current machine might result in the lowest total cost per unit produced for the remaining life of the mine.

Jan 1, 1982

By Martin H. Stanczyk

The Organic Act of 1910 established the Bureau of Mines and gave it authority and responsibility for conducting research on separation, recovery, and recycling of waste products and scrap generated by the mineral and metals industries and the consuming public.(1)1 It was apparent to our Nation's leaders even then that mineral resources, once mined, are irreplaceable and that the development of methods for recycling the values contained in wastes would be required to solve the problem of even¬tual scarcity, Estimates of the increase in per capita consumption of mineral resources in this country indicate that the consumption of metals, minerals, and fossil fuels by 1980 will be double that consumed in 1970 (2). The United States can expect to meet its future mineral needs in three basic ways: the first is through increased production of primary raw minerals; second by increasing imports from foreign sources; and third by recycling secondary materials and metals that were formerly discarded as waste. Rather than consider these

Jan 1, 1972

By Michel Bustamante

The Arbre viaduct, 200 metres long, is the most important structure on the Belgian portion of the High Speed Train line between Paris and Brussels. The particular geotechnical conditions of the soil with carboniferous limestone affected by karstic phenomena, has prompted the designer to found the viaduct on systems of high capacity vertical and batter micropiles. The design of the working micropiles was validated by full scale tests performed on instrumented micropiles. The size of the structure and the deformation criteria to be met when HS trains are crossing the viaduct, together with the lack of references for such innovative structure, called for monitoring the movements of the piers as soon as the link was open to traffic. The authors report on the results of loading tests on micropiles and the results of settlement structure monitoring for a period of 4 years. Settlement of the foundation is estimated taking into account the group effect.

Jan 1, 2002

By M. K. Yelloji Roa

Effect of conditioning with Thiobacillus ferrooxidans on the floatability of sphaierite and galena has been determined in this work. The flotation behavior of the conditioned minerals clearly shows that such bacterial conditioning does produce marked modification of their surfaces. The variables affecting the surface modification and thereby the flotation response of the minerals were found to be cell concentration used for bacterial conditioning, the period of biotreatment and the pulp density. Importantly, while the enhancement in flotation obtained due to sulphuric acid treatment was retarded by biotreatment in the case of galena at all cell concentrations due to electrochemical effects, such decrease occurred in the case of sphalerite only at cell concentration sufficiently high for their attachment to the mineral surface. The effect of bacterial conditioning has significant implications to the differential flotation of sphalerite and galena. Mechanisms responsible for the modification of the surface properties of these sulphides due, to bacterial conditioning are discussed.

Jan 1, 1991

By D. W. Lui

Tangdan copper oxide deposit, the largest independent copper oxide deposit in China so far, is located in the northeast of Yunnan province, southwest of China. The ore from this deposit is characterized by: low grade, high oxidation ratio, and fine-grained disseminated, resulting in poor flotation recovery. The analysis of plant flotation data reveals that the loss of copper minerals into tailings is mainly with coarse size fraction due to insufficient liberation and fine size fractions, especially minus 10 microns fraction, which proved to be very difficult-to-float with conventional flotation. In order to improve the performances of plant flotation of this ore, laboratory flotation tests were conducted with the pure malachite, which was the principle copper oxide mineral in Tangdan copper ore deposit. The results obtained suggested that a finer grinding (up to -325 mesh or even -400 mesh) be needed to decrease the loss with coarse size fraction, and vacuum flotation is a promising way for the recovery of the fine malachite effectively.

Jan 1, 2014

By R. L. Miller

The potential for recovery of enriched uranium from spent nuclear fuel which has been consolidated into a nuclear waste form was explored in the studies reported here. The waste form of interest is iron-enriched basalt (IEB)--a silicate-based, fused-cast ceramic. IEB samples were prepared containing fuel assembly materials that simulate the core debris of Three Mile Island Unit II;1,2 the nominal composition of the consolidated waste form is given in Table 1. Ore Types The IEB samples, or man-made uranium ores (MMUO), are in two different mineralogical forms. Each MU0 was made by melting the constituent materials and holding at about 1500°C for 1 h. The MMUOs were then heat treated to control crystallization and crystal growth and then cooled to room temperature.

Jan 1, 1983

By E. Z. Casassa

There has been a recent revival of interest in concentrated coal/water slurries as a substi¬tute for fuel oil or for coal/oil mixtures, particularly in electric power generation. The idea is not a new one. Coal/water slurries were transported by pipeline in the U.S. in the early nineteen-sixties, and the Black Mesa coal pipeline has been in operation for several years, while in Germany, coal/water slurries were being burnt for power generation in the early nineteen-seventies, as described by Merten and Höner (1972). Since coal is not a pure substance but a carbonaceous mixture, the different chemical and physical behavior of coal/water dispersions from different deposits must be understood in order to optimize the properties of the result¬ing slurry fuels. Since minerals which are minor constituents of coal may also strongly affect slurry properties, coal chemistry may vary considerably even within a single deposit. Thus it is unlikely that there will be a single formula for optimizing the slurry properties of all coals, and even the answer for coal from a single source may change with time.

Jan 1, 1983

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a roomand-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90%. But, the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing oversprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99% and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber.

By F. B. Kuhnow

When performing blasting operations in open pit settings, energy is released and transmitted through the geology. Some negative effects can have significant impacts on mining operations and adversely affect mine production. This technical paper presents recommendations for blast design to prevent damage due to ground motion from blasting on adjacent concrete structures of underground operations. The paper includes a case study describing a problem regarding an open pit mine expansion and asks whether production blasting will damage concrete shaft structures due to blast stress waves and blastinduced ground motion. Based on the results, a set of criteria is provided to implement in current and future mining operations that involve blasting near underground concrete structures. A set of techniques on how to improve vibration levels for safe operations is also presented. Knowledge of particle velocity and wave propagation for site-specific circumstances to determine a safe level of vibration is recommended. Emphasis is placed on making use of electronic detonators and early delay detonators to achieve successful levels of vibration. A dynamic analysis is necessary to determine if vibration from blasting can damage the concrete shaft structure. When reinforced concrete structures are subject to blast loading, both concrete and steel are subject to very high strain rates. As opposed to static loads, when subject to high strain rate loads these materials increase their strength significantly. In fact, they increase by more than 50% for reinforcing steel, by more than 100% for concrete in compression, and by more than 600% for concrete in tension. This finding is of significant importance in mining operations because it allows an increase in flexural capacity of individual members as a result of high strain rates. Therefore, an elevated ground vibration (PPV) or particle velocity is permissible when blasting takes place near concrete structures.

Jan 1, 2014

By Chi-Ming Chang

Alloy powders are commonly used in the purification of zinc sulfate solutions for use in standard electrowinning practice. The primary goal of this research was to study the use of zinc-lead alloys for similar reactions in the galvanic stripping of impurities from organic solutions. The effects of various parameters on the electrochemical behavior of commercially produced zinc-lead alloy powders were determined. A qualitative evaluation and summary of the influence of the more pertinent parameters on iron removal from di-(2-ethylhexyl) phosphoric acid (D2EHPA) by galvanic stripping is given. Water concentration, oxygen content and reaction temperature were the principal factors affecting the reaction rate and process efficiency. Activation energies were also calculated and indicated that the reaction changes from chemical to diffusion control .with increasing temperature in the range of 35" to 45°C. The results showed that zinc-lead alloy gave faster reaction rates with less sensitivity to process variables than SHG zinc as a reducing agent for galvanic stripping. The role of lead could be as cathodic sites for the reaction which enhances the zinc dissolution or anodic half reaction. The morphology of the zinc-lead alloy surfaces, before and after the reactions, supports this assumption.

Jan 1, 1998

By J. W. Hawkins, K. B. C. Brady, M. W. Smith

The Pennsylvania Department of Environmental Protection (PaDEP) has been issuing surface mining permits since 1984 that authorize remining in areas that will affect preexisting pollutional discharges. These permits require the mine operator to employ best management practices to reduce pollution loading from abandoned mine discharges. A total of 110 completed mining operations with 233 discharges were evaluated to determine the impact to water quality. Overall, acid loading from these discharges was reduced by 7,200 kg (15,900 lbs) per day or 61%. Metals loadings were also reduced. For acidity, 49% of discharges improved or were eliminated, 52% showed no significant change, and fewer than 1% got worse. Loading reductions resulted from a combination of reduced concentrations and lower flows.

Jan 1, 2002

By F. Heivilin

"Health and Safety problems can make a mineral deposit or a portion of one, an operating plant, or finished product unprofitable or worthless. Therefore they need to be reviewed when reserves are established and yearly thereafter until the deposit is closed down. Health and Safety regulations serve as a guide, but I have always done more frequent checks, when adding new products with different specifications or during times of bad weather and crisis. Water quality and quantity are always in question. Health and Safety are quality of life issues which are at or near the top of priorities for communities, companies, employees, and government bodies. Georgia dropped from one to three in U. S. for business development due to “Quality of Life” issues. Remember crystalline silica is present in nearly all sedimentary and acidic rocks and basic igneous rocks are the perceived home of asbestos. These health issues, any other safety and health issues or perceived issues need to be resolved initially and any time they come up during life of deposit. When handled properly good safety and health programs add to the profitability of a deposit, not to the costs. Daily safety checks in operating plants and mines, and visual check of all drilling core with an eye for changes are a key to successful programs. Both plants I turned around had terrible safety records, too much airborne dust, and maintenance problems resulting in low productivity. In almost every case cost reduction was tied to eliminating maintenance and spillage problems which caused health problems and increased possibility of accidents. Implementation of these safety and health programs around 1970 starting prior to government programs, working with new MSA/MSHA regulations, working to improve the regulations as a president of a state mining organization, and maintain profits was a challenge, but very rewarding. Reducing time to make repairs and work simplification gleaned from observations and employee recommendations learned from making multiple daily inspections resulted in years without lost time accidents at two plants, reduced maintenance and 33-75 % improvement in cost per ton at A. P. Green Refractories Co. Eufaula Calcining Plant 1972-77 and Oil-Dri Ochlocknee plant and mine 1979-82. The Ochlocknee mine worked 1981-2007 without a LTA. The author participated in 16 acquisitions and new plant design projects. All of above reduced costs allowed mining deposits with higher overburden to be used and considered. Thereby increasing reserves considered in all operations."

Jan 1, 2016

By P Lukic

The definition of the working sections that will be used in a mine is usually initially made in the field by the geologist supervising the drilling program. These initial definitions are often made on the basis of rules of thumb such as æcoal less than 30 cm thick cannot be mined separatelyÆ; æpartings more than 30 cm thick will be mined separatelyÆ; and æif a coal seam is less than 50 cm thick and the parting above or below is thicker than the coal, the coal will be wastedÆ. These decisions are also often made based on the requirement for a minimum sample mass for analysis, and the desire to collect data at the minimum resolution to conserve the exploration budget.In many cases the geological models based on this data are produced at a resolution that is inadequate to allow the mining engineer to produce a mine plan that will maximise project value. This problem is generally unrecognised.Where data is collected to a higher level of resolution the subsequent processes employed in the production of geological models and mine plans often discards the inherent value that is hidden in this data. Again this problem is generally unrecognised.This paper highlights this problem and then presents a methodology that ensures that the optimal working section is selected and compares the outcomes of applying this methodology versus adherence to the usual rules of thumb.

Sep 26, 2011

By M. Peshko, J. C. Gingerich, L. W. Matthews

"Noranda has successfully developed and implemented two leading-edge mineral exploration technologies — hyperspectral remote sensing and 3-D seismic surveying. Airborne hyperspectral imaging provides detailed geological and mineralogical mapping capability at both a regional and project scale that facilitates improved selection of prospective terrain and an accelerated exploration cycle. Noranda, in partnership with Falconbridge, has licensed the exclusive use of the Earth Search Sciences Inc. (ESSI) Probe-1 hyperspectral scanners (128- channel, 0.43 µm to 2.5 µm spectral range) that are capable of mapping in excess of 3500 km2 per day at 10 m pixel resolution. The technology has been successfully deployed on four continents over a broad range of terrain from desert to boreal forest and the high Arctic.To augment the company’s deep search initiatives, Noranda has successfully modified and implemented existing 3-D seismic technology to help targeting massive sulphides located at depths ranging from 500 m to 2000 m. In the fall of 1998 and early 1999, Noranda completed an 18 km2, 3-D seismic program in eastern Canada by successfully drill testing acoustic impedance anomalies locating massive sulphides at depths in excess of 1100 m."

Jan 1, 2002

By Timothy D. Stark

Jet grouting has increasingly become one of the ground improvement technologies used to address seepage concerns and to provide strength improvement of soils. The technique of jet grouting uses high pressure/velocity jet fluids to erode the existing soil and then to mix the cuttings with cement slurry to form soilcrete. Excess slurry or spoil is ejected to the surface. If the native soil is not completely mixed with slurry, the resulting columns will have soil inclusions which can reduce the strength of the column and/or increase the permeability of the column. A jet grout test program at Tuttle Creek Dam shows that the completed large diameter columns contain perhaps 40 to 50% or more of native soil that was not broken up and mixed during the jet grout process. The test program included excavation of full-scale columns to a depth of 35 ft (10.7 m) for visual inspection and testing. Additionally, six of the columns were cut or sectioned to investigate the interior of the columns. The observed inclusions include significant amounts of both fine grained (silts and clays) and coarse grained (fine sands and sands) soils. Evidence suggests at least two explanations: (1) fine grained soils can be difficult to erode and break up into small enough particles that can be ejected to the surface, especially if at low natural water content, and (2) when large diameter columns are being excavated, the excavated roof of the cylindrical cavity may be unstable and may collapse. With this roof instability large slabs of material can break off, fall into the slurry and escape the cutting and mixing action of the rotating jets. This paper describes the Tuttle Creek Dam test program, inclusions observed in the completed columns, and suggests potential causes of the inclusions.

Jan 1, 2009

By F. Bourgeois, J. -S. Kroll-Rabotin

ABSTRACT: Falcon concentrators are enhanced gravity separators designed for concentrating fine particles. The Falcon UF model is unique in that it is dedicated to beneficiation of ultrafines, one key feature being that it does not make use of any fluidization water. We investigated the physics of particle transport inside Falcon concentrators, and concluded that separation efficiency is governed by differential settling velocity. We derived and published a predictive model of the partition function under dilute conditions. We intend to extend the initial model to concentrated ultrafine suspensions for application to industrial scenarios by adding hindered settling to account for solid concentration effects.

Jan 1, 2011

By R. Brantley Sudderth

There are three broad categories in which most solvent extraction technology can be distributed?: 1) reagents, 2) equipment, and 3) systems. Reagents which are now used in commercial solvent extraction plants are of many chemical types, and each possesses certain properties which make it more economically desirable than another alternative. The equipment which is' used in solvent extraction plants for contacting the organic and aqueous phases and separating the same is varied. Most common to the industry is the mixer-settler unit which in itself, can be of varied design; but many new innovations in contacting and separating equipment have been recently introduced or are :now being studied. Each specific solvent extraction application will often dictate the type of contacting and separating equipment used. Obviously, the trend is toward smaller less expensive equipment which reduces the often expensive organic inventories necessary for most solvent extraction plants. The current thrust of .investigations in ancillary equipment is usually aimed at recovering organic from solvent extraction sludges or from aqueous streams exiting the process.6 This type of equipment helps to reduce the total organic losses from solvent extraction plants and thus reduce the operating costs. The term "systems" in solvent extraction applies to the manner in which a solvent extraction process is carried out. This manner is usually dictated by the properties of the reagent which is used, and it involves a tailoring of the equipment or the process flowsheet. Some of the things which can be tailored are: 1) The aqueous media -whether acidic or basic and what type of acid or base 2) Counter-current or single stage (co-current) contacting 3) EMF or pH control 4) Organic "crowding" alternative 5) Heating or cooling process streams Regardless of the type or extent of tailoring, efforts to do this are usually a result of the low cost of solvent extraction as a unit process.

Jan 1, 1977

By Christopher Mark

Six decades ago, the most dangerous job in the USA was mining coal underground. Roof falls were responsible for half of the deaths, killing about 100 miners every year. Fast forward to 2016 and zero roof fall fatalities. Just three miners were killed by roof falls during the following 6 years. How did the mining community achieve this historic goal? This paper starts by analyzing the roof fall fatalities in 1968, categorizing them by their fundamental cause. Then, it shows how each type of roof fall was reduced over time, using snapshots of the fatalities occurring in subsequent decades. Along the way, it evaluates the influence of the regulatory environment, changing mining methods, and better ground control technology. The study found that in 1968 more than half of roof fall fatalities at large mines were attributable to an inadequate safety culture. The immediate effect of the 1969 Coal Mine Health and Safety Act was to reduce the riskiest activities, like needlessly going under unsupported roof. Other hazards, like large roof falls, required technological developments before they were brought under control. Roof Control Plans, which the US Bureau of Mines had been advocating since the 1920s, played a significant role throughout the process.

Mar 12, 2024

By A. Ghirian

Once cemented paste backfill (CPB) is transferred and placed into a mine stope, various coupled mechanisms will take place in the CPB material or structure. It will be subjected to strong coupled thermal (T), hydraulic (H), mechanical (M), and chemical (C) processes. Field studies have shown that the in-situ properties and performance of CPB differ from those obtained in the laboratory. This is mainly due to effects of the aforementioned coupled THMC mechanisms or processes. For a reliable and cost-effective design of a CPB structure and barricade, it is crucial to have a proper understanding of the THMC behaviour and evolution of CPB. Also, it is important to consider the effect of coupled THMC factors (e.g., self-weight pressure, drained/undrained and thermal conditions, pore pressure) while curing the CPB specimens. For this purpose, a laboratory setup is developed to investigate the properties of CPB materials. The setup is capable of curing CPB specimens (10 cm in diameter and 20 cm in height) under controlled vertical pressure (curing under stress) and various coupled THMC conditions, while continuously monitoring the evolution of total stress, pore pressure, suction, temperature, water drainage, chemical composition of the pore water and vertical deformation. Once the required curing time is achieved, the specimen can be extracted and then subjected to experimental tests of interest, such as those that determine the Unconfined Compressive Strength (UCS), shear strength parameters, saturated hydraulic conductivity and thermal properties. In this paper, we describe the developed experimental setup and present some results of the THMC behaviour of CPB under various curing stresses and rates of backfilling. The obtained results show that the THMC properties of CPB are strongly coupled due to several mechanisms, such as self-weight pressure, heat of hydration and suction development as a result of self-desiccation. The findings can assist researchers and practitioners to better understand THMC behaviour and thus design more cost-effective CPB structures.

Aug 1, 2013