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By Roberto Waisberg I.

El presente texto refiere brevemente la historia del proceso de producción y costos del oro en las minas de Chile hasta el año 1956. Desde la llegada de los españoles al Perú, el prestigio de producción de oro en Chile despertó la codicia de los españoles, registrándose un aumento de producción de 2000 kg. entre los años 1545-1560, que posteriormente se reducirá a la mitad de los años restantes del siglo. Luego, en el siglo XVIII, la producción asciende de 400 kilos nuevamente hasta alcanzar los 3100 kg anuales. La guerra con España y el nuevo gobierno producen una decaída nuevamente en el oro, con promedios de 300 kg. Sin embargo, el periodo de 1931-1956 representa la etapa más importante enl la historia cuprífera de Chile puesto que el volumen de producción registra 6 000 kg. anuales. La contribución de este auge se debe a las medidas gubernamentales que buscaron resarcir la crisis económica producida en 1930, a través de la transformación de sus planteles de beneficio y posterior adaptación para la flotación de minerales de oro, asi como la construcción de plantas de cianuración, desarrollando la explotación en diversos yacimientos mineros. De otro lado, con el advenimiento de la Segunda guerra mundial la producción desciende a 2938 kg, siendo el valor más bajo registrado hasta 1933. Posteriormente y pese a la reducción de producción aurífera, hay un repunte del contenido del oro de minerales y concentrados, generando un incremento de la minería del cobre en los últimos años. En 1955, la producción anual de la pequeña y mediana minería establece un 73.8% para el primero, mientras que el segundo llega a 26.4% del total. El incremento adicional del oro dependerá de la ampliación de la planta fundicional de Paipote y de la Fundición de la zona central, estimándose un total de 1000 kg anuales. Así para interesar a los productores auríferos en la reiniciación de sus explotaciones, deben establecerse políticas de estabilidad en los precios que permitan afrontar los desembolsos de la instalación de las faenas y la rehabilitación de las minas.

Jul 20, 1959

The major copper orebody at Mount Isa is being extracted at a rate of four million tonnes per year. The method used requires an equivalent rate of back filling with (mainly) cemented fill. There were three major incentives for developing this mining system. The first was the prospect of high ultimate recovery of the orebody. The target is 100% recovery. Also the proposed stoping layout appeared to offer significant advantages in development and production costs. Finally, extensive subsidence above the northern end of the orebody could have disturbed permanent surface installations and jeopardised a possible future open cut. The full implications of this ambitious strategy were not apparent in the early years. Now, after twelve years of production the benefits are being realised and they can be weighed against the costs. Probably the most interesting result which comes from this analysis is the significance of cutoff grades and dilution factors in balancing mining and filling rates.

Jan 1, 1980

By D. S. van Vuuren

Industrial production of titanium occurs via the batch-wise reduction of titanium tetrachloride (TiCl4) with a reducing metal, being magnesium in the Kroll process, or sodium in the Hunter process. In the search for low cost titanium, the CSIR is developing a continuous process to produce titanium powder directly via metallothermic reduction of TiCl4 in molten salt, dubbed the CSIR-Ti process. The move to a continuous process has been attempted by a number of organizations, but was until now always met with failure, due in no small part to challenges inherent in the process chemistry. The reaction between TiCl4 and the reducing metal can occur directly, when TiCl4 or any titanium sub-chlorides present, comes into contact with suspended or dissolved reducing metal. The reaction can also occur indirectly, without any physical contact between the reacting species, via an electronically mediated mechanism. The reaction mechanism via electronic mediation can cause TiCl4 to react at the outlet of the feed port, rapidly causing blockages of the TiCl4 feed line. The electrical conductivity of the metal reactor can also cause the electronically mediated reaction to favour the formation of titanium sponge on the reactor walls and internals, rather than titanium powder. Various methods were investigated to overcome the problem of blockages in the TiCl4 feed line, e.g. mechanical removal, sonic velocities, dilution of the TiCl4 and the use of ceramic feed lines. This article discusses problems experienced with the continuous feeding of reagents, and various methods attempted are shown and discussed. Information is also given on the morphology, chemical composition and suitability of the final titanium powder for powder metallurgical application as presently produced by the CSIR-Ti process. Keywords Titanium dioxide, titanium nitride, carbo-thermic reduction, ilmenite, slag, tunnel kiln, residence time.

Jan 1, 2011

By Brian Hart, Rong Fan, Roger Smart, Andrea Gerson, Ning Xu

A complete strategy has been developed for identification of the reasons for losses in recovery and/or grade, due to changes or complications in mineralogy and in mineral surface conditioning, and their subsequent correction. The sequence of methods starts with comparison of mineral phases between QEMSCAN/MLA (compositional) and Rietveld XRD (crystalline diffraction) with bulk assay reconciliation. This methodology has recently led to identification of unrecognised amorphous content (12-40 wt.%), previously attributed to crystalline phases, in the fine fraction (<35 µm) of some problematic flotation feeds. Attached amorphous silica, talc- and chlorite-like fines have direct influence on the hydrophobic/ hydrophilic ratio on value mineral surfaces adversely affecting flotation. SEM/EDS is used in the backscattered imaging mode to determine possible problems with liberation (e.g. remnant local locking), not detected in standard liberation analysis, resulting in gangue flotation. EDTA extraction is used to assess bulk feed pre-oxidation and sequential oxidation product loading through the circuit. Changes in circuit solutions are assayed with speciation modelling of precipitates and potentially adsorbing species. ToF-SIMS with principal component analysis is then used to correlate surface species with specific minerals and can be used to assess the effectiveness of specific reagents particularly collectors. This approach identifies unwanted activating species and interference with value surfaces by adsorbed hydrophilic ions, precipitates and fine particles. When the interference or ineffective reagents are specifically identified, remedial action can be targeted. This method has identified residual talc-like layers (<10 nm thick) inducing gangue flotation of pyroxene and chromite in PGM flotation. Recent case studies of application of the full methodology to losses of molybdenite at KUCC and to sphalerite activation in the Cu/Pb circuit at Brunswick Mines with remedial action are discussed.

Jan 1, 2014

By L. Diels

About 45% of the contaminated sites are dealing with heavy metal problems. Metals are spread in the environment by mining activities, surface treatment and non ferrous processing. As heavy metals can not be degraded, removal or immobilization (leading to bioavailability reduction) are the only risk reducing measures that exist. The currently best available technique for remediation of heavy metal contaminated groundwater is to pump the contaminated water and to treat it in a wastewater treatment plant installed on the surface. Next to this often used, but expensive, pump and treat technologies, heavy metals can be immobilized by inducing sulfate reducing bacteria (SRB) to transform the sulfates, that are very often present in the same groundwater (due to the metal mining or processing activities), into sulfides. These sulfides will precipitate the metals as insoluble metal sulfides. At the moment several studies have demonstrated the feasibility of this In Situ Bioprecipitation Process (ISBP) for the removal of heavy metals from ground-water as well at lab scale (batch and column tests) as at field scale. However, some questions arise concerning the continuation of the process, the efficiency and the sustainability of the precipitates. The presented study will try to answer these questions. The study is based on more than 10 different studies, all done by the same authors, on different groundwaters and aquifer samples. The presentation will give an overview of the guidelines necessary for a correct and successful bioprecipitation process with stable metal sulfide precipitates. An important question in the ISBP is related to the sustainability of the heavy metal precipitates. It could be observed that the interruption in the carbon source delivery also stopped the in situ bioprecipitation process. Depending on the metal also some release from the precipitate could be observed. It was shown that release can occur with Co and Ni. Aquifers, on which the metals precipitated during the ISBP, were treated in a sequential extraction process under an-aerobic and aerobic conditions. It could be shown that especially under the anaerobic conditions the Zn and Cd precipitates changed from the leachable and the exchangeable fraction to the organic or Fe-Mn fraction (i.e. from the unstable to the stable fraction). The same could be observed for Co and Ni but still some fraction was present under a more available form. On the other hand it could be shown that large differences were observed concerning the heavy metal speciation on the aquifer in function of the used carbon source during the ISBP. The molasses treated systems showed a much more available heavy metal fraction on the aquifer compared to the lactate or HRC® treated groundwater. The different speciation forms based on the use of different carbon sources will be discussed in detail. It will pay attention to the influence of the carbon source, the efficiency of the induction of the bioprecipitation process, the influence on the competence between sulfate reducers and methanogenic bacteria and the influence of low pH on the ISBP. It seems that acetate, which is also a degradation product of fermentation of some carbon sources, can inhibit some sulfate reducers. Also the relation between slow release compounds and immediately available compounds will be explained. Finally a pilot study will be presented showing the problems that can be encountered during this process. Focus will be put on the induction of the process, the keeping on of the process and the follow up of the process by the installation of in situ mesocosm socks. These results will allow the correct implementation of the ISBP with an eye on longevity and sustainability of the process and present the ISBP as a much more sustainable alternative to the pump and treat technology as measure for heavy metals contaminated groundwaters.

Jan 1, 2006

By James C. Irvine

Meramec Mining Company's Pea Ridge underground mine is presently involved in a large scale pillar recovery program and has made use of both rotary and down-the-hole drills for large diameter blastholes. Groups of pillars have been blasted with water gels in massive blasts which have broken in excess of one million tons of ore per blast. An outgrowth of the pillar recovery program is the combination of rotary and down-the-hole drills to develop vertical "raises" between mine levels. This paper outlines the Pea Ridge procedure for pillar blasting including the use of non-electric caps. Techniques and loading rates are discussed, and safeguards against blasting damage which were developed as a result of the program are presented.

Jan 1, 1976

By d&apos, Dennis V. Andrea

The Bureau of Mines and El Paso Mining and Milling Co. conducted a cooperative in situ leaching research program at the Emerald Isle mine near Kingman, Ariz. The objective of this research was to develop in situ leaching methods for 200,000 tons of ore exposed in the pit bottom and also 3,000,000 tons of ore under 200 feet of overburden adjacent to the pit. The research included core drilling for fragmentation analysis, inplace permeability testing, seismic surveys, blasting tests, blast vibration measurements, inplace leaching, and ground water monitoring. A l5,000-ton test area in the pit bottom was blasted and leached inplace for 117 days. This successful test was followed by leaching 100,000 additional tons of unblasted pit bottom ore. Two test blasts, under 205 feet of overburden and extending to 290 feet, were detonated in an area near the open pit. The second blast was detonated because the first blast did not create adequate permeability for leaching. Pit bottom leaching was discontinued and the test area under 200 feet of overburden was not leached because the company terminated operations at the Emerald Isle mine. Based on the research completed, an expanded in situ leaching system was designed, but not implemented, to recover copper from a 1,500,000-ton area at the Emerald Isle mine.

Jan 1, 1977

By Tyler Luxner

Stillwater Mining Co. (SMC) is the largest primary producer of platinum and palladium in North America. SMC operates two underground mines in south central Montana, along the 45-km (28-mile) platinum/palladium J-M Reef in the Stillwater Complex. The Stillwater Mine exploits 9.6 km (6 miles) of deposit strike length and East Boulder Mine exploits 4 km (2.5 miles) of deposit length. The two mines are 20.4 km (12.7 miles) apart with SMC controlling a considerable length along the entire J-M Reef trace. Production at the Stillwater Mine began in 1986 and in 1988 the first tunnel boring machine (TBM) was commissioned, becoming an integral part of mine development at SMC. TBMs have been used for developing production footwall laterals (FWL) to access new mining blocks at the Stillwater Mine, as well as boring twin crosscut ac-cess tunnels at the East Boulder. Two TBM development expansion projects are currently in progress: the Graham Creek project at the East Boulder Mine, which will extend footwall lateral development 2,591 m (8,500 ft) to the west, and the Blitz project, where a TBM will be commissioned to extend east out of the Stillwater Mine to 3,658 m (12,000 ft) beyond the current production mining front. General strike and dip of the Reef is west to east and to the north, respectively.

Jan 1, 2012

By G S. C Murray

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutionsÆ funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industryÆs concept of the unwritten æsocial licence to operateÆ is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007

By Ancel St. John

Defects in the interior of metal objects are troublesome to both manufacturer and user. For the former, they frequently increase manufacturing cost through the rejection of material when defects appear after considerable work has been done. For the latter, they often cause damage to equipment, personal injury, or loss of life when a part, which has passed all inspections and has been put in service, gives way because of a hidden flaw. Methods of testing that locate such flaws without subjecting the specimen to possible, if not actual, destl-uction are few; x-ray examination, whether fluoroscopic or radiographic, is one. Hitherto, however, x-ray examination has been restricted to objects of nearly uniform thickness and regular outline; the inspection of such articles as those shown in Fig. 1 has been inconvenient and unsatisfactory. This figure represents a group of 5/16-in. hexagonal-head machine bolts,

Jan 1, 1923

By Ancel St. John

Defects in the interior of metal objects are troublesome to both manufacturer and user. For the former, they frequently increase manufacturing cost through the rejection of material when defects appear after considerable work has been done. For the latter, they often cause damage to equipment, personal injury, or loss of life when a part, which has passed all inspections and has been put in service, gives way because of a hidden flaw. Methods of testing that locate such flaws without subjecting the specimen to possible, if not actual, destl-uction are few; x-ray examination, whether fluoroscopic or radiographic, is one. Hitherto, however, x-ray examination has been restricted to objects of nearly uniform thickness and regular outline; the inspection of such articles as those shown in Fig. 1 has been inconvenient and unsatisfactory. This figure represents a group of 5/16-in. hexagonal-head machine bolts,

Jan 1, 1923

By J. Vaughn Barrie

Placer mineral deposits may exist in the nearshore and shelf regions off western Canada. These deposits could contain gold, ilmenite or zircon as well as sand and gravel aggregate. Two deposit types typical of the British Columbia offshore are: (l) modem and relict gold/titanium beach deposits; and (2) reworked relict titaniferous shelf deposits. The preservation of drowned beach heavy mineral concentrations resulted from a rapid relative sea level rise across the shallow shelves approximately 10 500 years ago, particularly off the Queen Charlotte Islands. This same transgression submerged an outwash fluvial system that had been exposed for at least 3200 years, draining areas of known gold placers.

Jan 1, 1994

By William H. Pomroy, Annie M. Carigiet

This U.S. Bureau of Mines publication is an analysis of underground coal mine fire incidents occurring in the United States during the 15years from 1978 through 1992. The fire data used in this analysis were obtained from U.S. Mine Safety and Health Administration mine fire investigation reports. Fires were analyzed by year, State, coalbed thickness, mine size, mining method, ignition source, burning substance, location, equipment involved, detection method, time of day, time of year, number of injuries and fatalities, method of extinguishment, and evacuation measures taken. In all, 164 fires are included in this report, or an average of 10.8 fires per year. The most fires occurred in West Virginia, Kentucky, and Pennsylvania, respectively. However, the fire incidence rates for these States, expressed as the number of fires per million tons of coal mined, were the lowest, second lowest, and fourth lowest of all underground coal producing States. The most common ignition source was electricity; the most common burning substance was coal; the most frequent fire location was the belt entry; the most common equipment involved in fires was the conveyor belt; and the most common extinguishing agent was water.

Jan 1, 1995

By Bhattacherjee A, Makesh S

Mechanised sub-level stoping is one of the most widely accepted stoping practices followed in base metal mines in India. As a general practice, blast-scheduling of rings in these stopes is done either heuristically or randomly which leads to a high fluctuation in ore grade when drawn and delivered to the mill. In this paper, dynamic programming has been investigated as an optimisation technique for optimal blast-scheduling of rings. A microcomputer based dynamic programming algorithm has been developed in C language which runs under the UNIX environment. A case study based on Indian mine data is presented to demonstrate the application of the dynamic programming concept and use of the developed software. It is concluded that dynamic programming can be used as a production planning tool in Indian mines practicing sub-level stoping and following heuristic/random approaches for blast-scheduling of rings.

Jan 1, 1995

By J. A. Jr. Church

I. EARLY FURNACES. COPPER blast-furnace construction in America has long recognized a general standard in the rectangular mater jacketed shaft with separate forehearth. The details, however, and especially those relating to shaft dimensions, have had to meet a great variety of conditions, and show no uniformity whatever. Selecting a few of the present day Western plants, we find furnace lengths varying from 12.5 to 87 ft., widths at tuyere level from 42 to 84 in., and heights above tuyeres from 5 ft. 4 in. to 22 ft. 4 in. ; and comparing present designs with those of the past, we meet contrasts no less striking. Unlike its transverse section, the length of a furnace has come to depend rather on the size of unit desired than on the requirements of smelting ; and if the question of length be ignored, several of the various existing designs can be grouped together on the basis of a common transverse section. This section, having a width at tuyere level of 56 in. and a height above tuyeres of 18 ft., was developed at Great Falls, and the story of its development contains some interesting features. Ground was broken for the Great Falls works in the spring of 1891. About a year later, the concentrator was able to begin operation, followed within the next few mouths by the Brueckner, reverberatory, and converter departments, and in April, 1893, by the first blast fur-

Jan 7, 1913

By Farrel W. Lytle

An X-ray emission spectrographic method of analysis is presented for determining rare-earth elements in fractions obtained from bastnaesite ore. The method includes determination of yttrium, thorium, lanthanum, and the rare-earth elements in various complex mixtures. The analysis technique is based upon comparing the samples with synthetic standards approximating the composition of the samples. Working curves are plotted on an absolute-intensity basis, with no correction for back-ground. Examples of working curves and the analyses of typical rare-earth concentrates are included. The selection of spectral lines for the various sample matrices is discussed. A special technique is used for samples in which rapid hydration and carbonation occurred. By analyzing synthetic samples of known composition, the accuracy of the method was determined. The average error of analysis was about 3 percent of the amount present in the range from 5 to 100 percent and about 7 percent in the 0.2-to 5-percent range. A maximum of about 40 samples per day may be analyzed for 7 elements each.

Jan 1, 1957

By H. E. Rorschach

Activity in Oklahoma fields declined in 1938 from the banner year of 1937. During the year, 1768 wells were completed as compared to 2632 completed during the year 1937. The following tabulation sets out details regarding the wells completed during the year: These computations do not take into account the wells drilled for repres-sure and salt-water disposal, and other nonexploratory wells. Purchasers&apos; reports filed with the Corporation Commission of the State of Oklahoma show a total of 168,789,229 bbl. of oil purchased from Oklahoma leases in 1938, or a daily average of 462,436, a decrease of about 25 per cent from the year 1937. The outstanding operation of the year was the further development of the Ramsey pool, in western Payne County, the producing horizon being classified as the Wilcox. This pool was discovered on the last day in the year 1937, by the Mid-Continent Petroleum Corporation drilling on a unitized block in see. 18, T. 18 N., R. 2 E. The map in Fig. 1 shows the development at the end of the year 1938. An important discovery of the year was the Champlin Refining Company&apos;s No. 1 Boehm, in Garfield County, sec. 4-24N-8W., the producing horizon being the second Wilcox found at a depth of approximately 6700 ft. This pool was assigned the name of Hillsdale. Some of the offsets to this discovery well had not come up to expectations at the end of the year, but the discovery seems to be important as indicating that the Wilcox sand is productive in the Anadarko Basin area, providing that the right structural conditions are present.

Jan 1, 1939

By H. E. Rorschach

Activity in Oklahoma fields declined in 1938 from the banner year of 1937. During the year, 1768 wells were completed as compared to 2632 completed during the year 1937. The following tabulation sets out details regarding the wells completed during the year: These computations do not take into account the wells drilled for repres-sure and salt-water disposal, and other nonexploratory wells. Purchasers&apos; reports filed with the Corporation Commission of the State of Oklahoma show a total of 168,789,229 bbl. of oil purchased from Oklahoma leases in 1938, or a daily average of 462,436, a decrease of about 25 per cent from the year 1937. The outstanding operation of the year was the further development of the Ramsey pool, in western Payne County, the producing horizon being classified as the Wilcox. This pool was discovered on the last day in the year 1937, by the Mid-Continent Petroleum Corporation drilling on a unitized block in see. 18, T. 18 N., R. 2 E. The map in Fig. 1 shows the development at the end of the year 1938. An important discovery of the year was the Champlin Refining Company&apos;s No. 1 Boehm, in Garfield County, sec. 4-24N-8W., the producing horizon being the second Wilcox found at a depth of approximately 6700 ft. This pool was assigned the name of Hillsdale. Some of the offsets to this discovery well had not come up to expectations at the end of the year, but the discovery seems to be important as indicating that the Wilcox sand is productive in the Anadarko Basin area, providing that the right structural conditions are present.

Jan 1, 1939

By T Roberts, S Talu

Steel wire weld mesh is a common industry standard surface support used in underground mining, traditionally installed with mining drills during the bolting cycle. As underground mining depth and stress increase, mining methods and their sequences at these depths place challenges on conventional surface support options. These challenges have provided a need for high capacity surface support options that improve development efficiency, reduce the need for secondary ground support installation and is easily installed with current mining equipment. A 5m2 mesh testing machine was built, suspending a 9500kg concrete slab, designed with multiple hold down points to test varying bolting patterns. Mesh load and displacement is accurately measured using a data acquisition system which pushes against the restrained mesh module with an available 200kN load and 1200mm displacement capacity. A testing program comparing conventional surface support, straps and combinations of both were tested for baseline results. New module designs incorporating existing mesh types and new design concepts were manufactured to allow for single pass installation during a bolting cycle. Nine mesh types, mesh/strap combinations and new mesh module designs were compared using the same test method. Based on these results, two high capacity mesh module types are produced. This paper will detail the test program, load and displacement results and underground mesh module performance, describing the two high capacity mesh modules function within the development cycle and manual handling. CITATION:Roberts, T, Talu, S and Wang, Y, 2018. Design and testing of high capacity surface support, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 303–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Lauri Pesonen

"Although electrical energy use at copper smelters is typically about 15-20% of operational costs, it is something which is not very often analyzed and discussed at a detail level in technical papers and presentations. This paper aims to list different equipment configurations per smelter area and estimate their electrical energy consumptions versus unit of material processed. In addition chosen smelting technology and oxygen enrichment rates affect the overall electricity consumption and therefore some overall guidance is provided for efficiency gains.INTRODUCTION In principle, processing plants, such as copper smelters, require electrical and chemical energy together with some degree of human input to process input materials into desirable output form like metallic copper. From the standpoint of metallurgical plant designers, the thermodynamics of smelting, when it comes to releasing and conserving thermal energy, is sufficiently understood and frequently discussed in the literature in detail, but judging from the quantity of publications, the way how we exactly utilize electrical energy is not. This article is meant to illustrate how electrical energy consumption is distributed among different process units and equipment types at copper smelters using various smelting technologies. In general, typically about 15-20% of operational costs are related to electricity and at locations with high electricity prices the potential savings can be quite significant for the overall profitability of the plant operations. In today’s tight profit margin environment any potential savings are more than welcome. The purpose here is not to promote any certain copper smelting technology, but to open a discussion on how and where we use electrical energy, and how the overall energy use could be lowered with the implementation of newest electric power saving designs and solutions. Using the principles outlined in this article, it should be fairly easy and straightforward to replicate the calculations and even improve them wherever it is seen necessary for the greater benefit for us all in this industry"

Jan 1, 2017