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By A. Cabañas

"In this paper, geostatistical techniques are applied to forecast the annual copper price in the short and medium terms (from one to five years ahead). These techniques allow the incorporation of monthly and multivariate information in the analysis and provide more accurate results than traditional approaches, especially as far as the one-year forecast is concerned.A second advantage of geostatistics stems from its ability to assess the uncertainty associated with the unknown future prices, thanks to estimation variances or confidence intervals, depending on the technique used. Such an assessment has a crucial importance in decision-making, from both macroeconomic and microeconomic points of view. IntroductionThe copper price traded in the London Metal Exchange is a relevant parameter for defining macroeconomic policies of producing countries like Chile. It is also a key factor for the mining companies, since fluctuations in the sell price affect the expected financial flows. Due to the amount of money involved in decision-making, it is necessary to have accurate forecasts of the future copper prices and to quantify the uncertainty associated with such prices.This paper focuses on the annual copper price estimation in the short and medium terms, i.e., from one to five years into the future. Henceforth, the word “estimation” will be used as a synonym of “forecast,” according to the geostatistical jargon (Matheron, 1989).Two main approaches, based either on statistics or econometrics, are currently used to forecast commodity prices, but both of them are not very accurate when applied to copper. First, the main methods are briefly reviewed, then the geostatistical formalism will be presented. So far, the latter approach hardly has been used to estimate commodity prices, although it may reconcile both statistics and econometrics via (1) the use of a stochastic approach and (2) the handling of ancillary variables related to the copper market. Another advantage of geostatistical techniques is the ability not only to forecast the copper price, but also to measure the uncertainty associated with it."

Jan 1, 2004

By Virgil Marple

In the summer of 1979 the University of Minnesota Mobile Laboratory (UMML), designed for the analysis of airborne particles and gases was used to study fugitive dust from an open pit coal mine. The analysis consisted of determining the particle size distribution and concentration of dust from various mining operations, such as blasting, draglines, loading, roadways and bottom scrapers. For some operations the particles size distribution and concentrations were determined at varying distrances. Details of the dust concentration within the plumes as the plume passed the UMML were measured with an optical particle counter. For line sources, such as roadways this enabled the calculation of the particle flux at the sampling location. In addition to the standard instruments associated with the UMML, the applicability of some new instruments were investigated. These included a uniform deposit cascade impactor and a flux meter. Finally, a technique in identifying plume origins which utilized elemental X-ray flourescence analysis of filter samples was shown to be effective.

Jan 1, 1980

By Jan E. Nesset, James A. Finch, Frank Rosenblum, Rebecca Payant

"Under certain conditions of moisture and oxygen, sulphides can spontaneously heat, a phenomenon known as self-heating. In this paper, we test a hypothesis that galvanic interaction between some sulphides can promote self-heating. Galvanic interaction is controlled by restpotential difference between minerals and their surface area of contact (particle size). In order to decrease rest-potential, four sulphides were tested: pyrite, chalcopyrite, sphalerite and galena. Two series of samples consisting of mixtures of two sulphides, each representing a mass fraction of 50 %, were run in standard self-heating tests. The first series comprised five mixtures, two with low rest-potential difference (pyrite-chalcopyrite and chalcopyrite-sphalerite) and three with high rest-potential difference (pyrite-galena, chalcopyrite-galena and pyrite-sphalerite). The second series was performed on a pyrite-sphalerite mixture at four particle sizes (80 % passing 850 µm, 300 µm, 75 µm and 38 µm). The first series showed that the individual sulphides and the mixtures of low rest-potential difference did not self-heat but the mixtures of high rest-potential difference did self-heat. The second series showed that self-heating increased inversely with particle size (increased specific surface area) and revealed that it was the fineness of the pyrite (high rest-potential sulphide) that governed the self-heating effect, indicating the rate-limiting step is the reduction reaction on pyrite (cathodic mineral). The increase in self-heating with high rest-potential difference and increasing particle fineness supports the hypothesis that galvanic interaction contributes to sulphide self-heating. A possible mechanism based on the hydrogen sulphide hypothesis is proposed where the reduction reaction at the cathodic mineral surface is ferric to ferrous. The understanding gained will be of interest to those involved in storage, shipping and disposal of sulphide minerals.INTRODUCTIONSulphide mineral ores are the major source of most base metals such as copper, zinc, nickel and lead. Once the ore is extracted, the sulphide minerals are liberated by size reduction (crushing and grinding), concentrated by flotation, and the concentrates sent for further processing to extract the metal (smelting and refining). At the various stages from mining to concentrate shipment and tailings storage, the sulphides are exposed to a variety of environments, which under certain conditions of air (oxygen), humidity and temperature can cause them to heat. Since no external heat source is involved, this pyrophoric process is known as spontaneous heating or, more commonly, self-heating. The self-heating of sulphides is associated with oxidation reactions under moist conditions. If the heat generated is greater than the heat dissipated, the sulphides will self-heat and the material temperature will rise. This can make working conditions potentially dangerous as oxygen is consumed from the surrounding air and significant quantities of sulphur dioxide (SO2) can be released (Ninteman, 1978)."

Jan 1, 2011

By R. Rampersadh

Paper written on project work carried out in partial fulfilment of B Eng (Metallurgical Engineering) degree Steel was sampled after calcium treatment, to follow changes in inclusion composition during the processing of alumium-killed steel into continuously-cast billets, at Mittal Vereeniging. There is some shift in the distribution of inclusion compositions towards alumina, as the liquid steel moves from the ladle to the tundish. This shift may reflect some reoxidation. However, the effect on inclusion modification is small, since only a small fraction of the tundish oxide inclusions is fully solid?which agrees with the plant observation that these heats cast without clogging. Magnesium oxide in the inclusions contributes to liquid formation, substantially increasing the range of lime: alumina ratios over which the inclusions are partially or fully liquid.

Jan 1, 2006

By W. M. Dressel

This Bureau of Mines report describes a shaft closure demonstration project in which 11 inverted pyramid-shaped plugs were used to plug abandoned open mine shafts in Galena, KS, The inverted pyramid-shaped forms, fabricated from steelplate, were designed so that the inverted base would be larger, by 4 ft on a side, than the approximate size of the shaft opening at the surface residuum-solid rock interface. After the surface openings of the shafts were trimmed with a backhoe, the steel forms, complete with reinforcing, were lowered into the openings and filled with concrete; the remaining portions of the openings above the plugs were backfilled to slightly above the surrounding surface level with waste rock and soil. Location and elevation monuments were installed for long-tern evaluation of the success of the project.

Jan 1, 1985

By H. S. Price

This report discusses the development of a mathematical model that describes the flow of methane only and methane and water in a coal bed during mining operations. Because of the complex geometry, boundary conditions and fluid properties, the model is based on a numerical solution to the equations describing flow. The goals for the development of this model and requirements to which it complies are for the most part expressly stated in Request for Proposal No. 50110752. In addition to the capabilities specified under the scope of work the model can handle an anisotropic porous medium and a source term has been added which will simulate, somewhat, the effects of desorption. This term will be pressure dependent. The effect of time on such a term is only taken care of in the change of pressure with time. This source term will have the dimensions of Mcf/day/Mcf pore volume. It will be a part of the input data to be supplied by the user and will be entered as a table of rates versus pressure. These models consider the fracture system as the main porosity. All computed results pertain to the fractures. The source term mentioned above represents the flow from the matrix porosity into the fracture. Such flow should be small compared with the flow between fractures since these models handle only one porosity structure system.

Jan 1, 2012

By F. V. Antonio, R. S. Pizarro

Masbate Gold Mines, dormant since WWI I, are now back in operation. The ore treatment plant incorporates carbon-in-pulp processing, utilized because of the ready availability of coconut shell charcoal in the Philippines and the high clay content of the ore. A detailed description of the plant, including the surprisingly fast and efficient alcohol stripping facility is presented. Operating data for the plant is provided together with an interesting performance evaluation of mechanical versus air- lift agitated leach tanks.

Jan 1, 1981

By Richard Dahl, Richard P. Taylor, David H. Watkinson

"Abstract - Detailed mapping of the Eastern Gabbro, Coldwell Complex, Ontario, revealed that the copper and platinum-group-element deposit on the Marathon property is confined to a coarsegrained to pegmatitic gabbro-diorite intrusion, the Two Duck Lake intrusion (TDLI). Exposed along the eastern boundary of the Coldwell Complex, the TDLI was emplaced as a sill whose orientation is slightly oblique to the general structure of the Eastern Gabbro. The TDLI has been subdivided into lower, middle and upper sub-units on the bases of lithological, textural, mineralogical, and geochemical criteria. Both border sub-units are sulfide-, base- and precious metal-enriched, and exhibit abundant evidence of host-rock assimilation. The primary mineral assemblage in the TDLI is plagioclase, olivine, clinopyroxene, Fe-Ti oxides, with accessory orthopyroxene, biotite, apatite; this primary mineral assemblage is essentially preserved in the core of the intrusion (i.e., the middle subunit). The Cu-PGE Marathon deposit, delineated mainly in the upper sub-unit of the intrusion, consists of disseminated Fe-Cu-Ni sulfides, and platinum-group-minerals derived by hydrothermal remobilization from primary magmatic sulfides. Enrichment in Cu and PGE resulted from partial replacement of original Fe-Ti oxides and pyrrhotite in the primary mineral assemblage by reaction with (a) residual magmatic fluid, and (b) fluids derived from the breakdown of host rock xenoliths and hydrothermal alteration along the lower contact of the TDLI. Résumé - La cartographie détaillée de l’Eastern Gabbro, Complexe Coldwell, en Ontario, révèle que le gisement de cuivre et éléments du groupe du platine de Marathon est confiné à une intrusion gabbro-dioritique, de grain grossier à pegmatitique, l’intrusion Two Duck Lake (TDLI). Cette intrusion s’est mise en place sous la forme d’un filon-couche légèrement discordant sur la structure de la bordure orientale de l’Eastern Gabbro. On y distingue trois sous-unités, inférieure, centrale et supérieure, sur la base de zonations lithologique, minéralogique et géochimique. Les sous-unités marginales sont enrichies en sulfures, métaux usuels et précieux, et montrent de nombreux indices d’assimilation des roches hôtes. La paragenèse minérale primaire inclut le plagioclase, l’olivine, le clinopyroxène, les oxydes ferro-titanés et accessoirement et localement, l’orthopyroxène, la biotite et l’apatite : cet assemblage est surtout préservé au coeur de l’intrusion (sous-unité centrale). Le gisement de Cu-EGP de Marathon, situé principalement dans la sous-unité supérieure, comprend une minéralisation disséminées à sulfures de fer, cuivre, nickel, et minéraux du groupe du platine, dérivés de sulfures magmatiques primaires par remobilisation hydrothermale. L’enrichissement en Cu et EGP résulte du remplacement d’oxydes ferro-titanés primaires par réaction avec des fluides tardi-magmatiques, et des fluides assimilés le long de la bordure inférieure de l’intrusion, dérivés de la fusion partielle des xénolites et de remobilisations hydrothermales."

Jan 1, 2001

By E. Galán

The largest Spanish kaolin deposits formed on granites occur in Galicia (NW Spain) due to a widespread kaolinization of Variscan granitoids. This paper provides insight of the origin of this kaolinization process on the basis of a mineralogical and geochemical study carried out in two kaolin deposits, presently mined to be used in the paper industry. Mineral composition of the deeply kaolinized rocks is dominated by well-ordered kaolinite with minor quartz, K-feldspar, mica (illite/muscovite), locally gibbsite, and traces of resistant accessory phases (rutile, ilmenite, zircon and monazite). The content and structural order of the kaolinite decrease with depth. Kaolinite formed by extensive replacement of feldspars (plagioclase). Differential mobilization of major and trace elements during kaolinization has been inferred by using a mass-balance approach. Significant amounts of Na, Ca and minor Mn, Sr, P and U were removed from incipiently leachable minerals (plagioclase and apatite), and K, Rb, Cs and Ba were released from K-feldspar and mica. On the contrary, Ti, Zr, Th, Hf and the REE are retained in the resistant trace minerals that are concentrated in the fine fractions of the kaolins.

Jan 1, 2010

By Woodcock J. T

During the dissolution of gold in fully aerated cyanide solutions the CN ion is the active agent, and consequently the usual method of evaluating the dissolving power of such solutions is to determine the CN- concentration analytically. The presence in the solutions of copper and/or zinc which themselves form complex cyanides, may result in erroneous conclusions as to the free cyanide ion concentration determined by titration.In this paper the theory of titration of such solutions has been developed, and potentiometric methods have been used to follow the behaviour of complex cyanides of copper and zinc. The results for cuprocyanides show Cu (CN)s to be the most important copper complex, and in addition they explain the reported low rates of solution of gold in copperbearing solutions which when titrated in the usual way, appear to have adequate free cyanide. An explanation of the misleading value of the titration is given, and suggestions for recognition of the condition are offered. Preliminary results for zinc-bearing solutions show that there is no satisfactory end-point for the titration of CN- in excess of that in the complex Zn (CN) 4=, which dissociates to CN and Zn(CN)g-.

Jan 1, 1950

By Arthur F. Taggart

TO all Mineral Dressers, but particularly to those in the Coal and Industrial Minerals Divisions: Ted Counselman, retiring after two years at the helm of the Milling Committee, pointed with pride to the continued growth of that committee, and sang the swan song "Why ain't we a Division of Mineral Dressing?" Our genial Secretary pointed out, handily, that, you see, the way the Institute is divided there are several blocks running across this way here, and one running all the way down here, and another running part way down here, and they all cut across each other like this, and anyway the miners want to be a Division now, so why not you Mineral Dressers be good and not upset the big Institute organizational chart? And anyway again, Divisions have vested interests, and a Division of Mineral Dressing would take something away from Coal and something from Industrial Minerals, and any good institutional man can see that a Division would never give anything up. It was all quite confusing, and apparently not too convincing, because then the Milling Committee went ahead and voted unanimously it is a good idea, let's see what the other fellows think about it as well.

Jan 1, 1944

By R. P. Maloney

Since mining operations began in 1900, Government geologists and mining men have periodically recorded the presence of the minerals of mercury and antimony in the extensive gold placer deposits near Flat in the Iditarod district of the Yukon River region, Alaska. No serious effort was made to recover the cinnabar contained in the gold placer gravels, and there is no evidence that veins of cinnabar and stibnite exposed in the placer operations (as reported by the Geological Survey) were ever explored or developed. A large monzonitic intrusive, which is the dominant geologic feature of the immediate area, is believed to be the lode source of the valuable minerals in the placer deposits. In contact with the monzonite are argillite and quartzite, metamorphic products from the Cretaceous shales and sandstones.

Jan 1, 1962

In 1992, the United States economy grew at a rate of 2%. The Gross Domestic Product rose to $5,946 billion. With 257 million people - 635,000 in mining including petroleum - the United States has more than 100 million dwelling units and more than 190 million licensed motor vehicles. New private housing starts rose I 1 % to 1.2 million units. New car production rose 4% to 5.7 million units. Truck and bus production rose 20% to 4 million units. The rate of inflation was 3.5% and the prime rate of interest was 6.25%. The Producer Price Index (1982 =100) was relatively unchanged from 1991 as follows: fuels and related products and power 80, metals and metal products 119, chemicals and allied products 126 and nonmetallic mineral products 117. Energy Imports of crude and refined petroleum, costing $50 billion, rose 3% to 455 Mm3 (2.9 billion bbl). Domestic petroleum production fell 1 % to 582 Mm3 (3.5 billion bbl). Petroleum supplied about 41 % of US energy, natural gas 24% and coal 23%. Coal production, 60% from surface operations, rose 1 % to 914 Mt (1 billion st). About 78% was used to generate electricity and 3% was coked. Exports valued at $4 billion included 57 Mt (63 million st) of metallurgical coal and 39 Mt (43 million st) of steam coal. Ura¬nium mining, including recovery from phosphates, fell 18% to 3 kt (3300 st) U308.

Jan 1, 1993

By D Macdougall, J Otto

The financing of large mining projects in developing countries is often achieved, at least in part, by limited-recourse financing methods. Financing agreements are affected by the basic accord that is struck between the host government and the sponsors of the project. It is concluded that governments and project sponsors should take into account the requirements of lenders when structuring such mineral development agreements to maximise the potential for attracting project financing. Lenders are likely to be most interested in aspects such as fiscal arrangements, calculation of taxable income and general accounting rules, royalties, transferability of payments/dividends overseas, corporate structure and control, staged development, financing, loan support and state guarantees/approvals, political risk, provisions for default, product marketing, settlement of disputes and environmental issues

Aug 1, 1994

By T. J. Goff, G. M. Denton

Mintek has developed the EnviroplasTM process for the treatment of solid wastes from the metallurgical industry, especially steel plant dusts, without requiring agglomeration to produce inert slag and at the same time recover metal values such as nickel, chromium and zinc. The products that are generated in the plasma-arc process are usually a metal and a non-toxic slag, which are tapped from the furnace in liquid form. The metal is mainly composed of chromium, nickel and manganese. During the production of stainless steel between 30 and 70 kg of dust and fine waste is generated per ton of steel. Mintek has successfully processed around 1000t of AOD/EAF dust on a toll treatment basis in order to recover the contained Cr and Ni. The metal produced contained 18.5 per cent Cr, and 5.5 per cent Ni. All slag samples tested conformed to US EPA regulations for disposal. The chromium and nickel recovery to metal was 90 and 98 per cent respectively, on a once through basis i.e. no baghouse dust recycle. Slag tapping temperatures varied between 1650°C and 1750°C. The average actual energy requirement excluding furnace heatlosses of smelting steel plant dust with anthracite as reductant was 1.36MWh/ ton of dust. The total mass of feed reporting to the off-gas stream was 10 per cent. The average ZnO content of the fume was 35.5 per cent.

Jan 1, 2004

By Walter E. Lewis

The Fort Randall Reservoir project, on the Missouri River at Pickstown, S. Dak., was designed by the Corps of Engineers and is part of the Missouri River Basin Development Program. The location of the project with respect to adjacent features is shown' in figure 1. When the project is finished, it will include a large earthwork dam and 12 circular tunnels, 8 of which will be equipped for power and 4 for flood control. Various phases of the construction have been contracted to independent companies, and at present four companies are working on different phases of the project under a rigid time schedule. Western Contracting Corp. is the contractor on stage II, earthwork; Johnson-Winston Construction Co. is the contractor for construction of the intake towers at the upstream side of the dam; McCarthy Improvement Co. has the contract for the power house and the outlet works on the downstream side; and Silas Mason Co. has the contract for driving the power and flood-control tunnels. The latter two companies use the same roads for ingress and egress to their respective work areas and the same general waste dump area. Under such circumstances, it is necessary that each company stay on a time schedule in regular sequence to avoid interference with the other.

Jan 1, 1951

By John J. Sammarco

Mining has one of the highest annual average fatality rates among major US industries. Health and safety dangers have been inherent to mining since the early days of picks and shovels. Even though miners’ health and safety has improved over the years, mining is still one of the most dangerous occupations. Mining was traditionally a low tech industry. It is now driven by competitive pressures to go high-tech by using programmable electronics (PE) for machine control, atmospheric monitoring and material processing. The industry’s experience with the functional safety of PE is limited compared with other industries. Thus, PE is an emerging technology for mining that can potentially create or worsen hazards.

Jan 1, 1999

By J. Luxford

The last decade has seen an enormous increase in the use of contractors right across the Australian mining industry. So much so that contractors now operate 33 of the 68 underground metalliferous mines around Australia and are making significant inroads into iron ore in the west and coal in the east. Safety used to be a low priority for many contractors. The picture has changed dramatically in recent years as most contractors take a far more professional approach to safety management. This paper examines the changes that have occurred and the requirements for effectively managing safety in a contracting environment.

Jan 1, 2000

By Arthur W. T. Grimley

Hydraulic coal mining is being successfully practiced in China, U.S.S.R., Japan and Canada and in each country, excepting Japan where suitable sites are not available, the system is being expanded to either existing conventional mines or new mines. Productivity levels and economics at these mines are in all cases better than the productivities achieved in conventional mines in the same general localities. In the U.S.S.R. face productivities approaching 50 tons per man shift have been reported while in Canada the latest statistics show average face area productivity levels are in the region of 200 tons per man shift production monitor. In the United States hydraulic mining has not been actively pursued to the same degree and consequently there are no full scale hydraulic coal mines in operation or construction. Because many of the coal measures in the Western U.S.A. are generally somewhat similar to those being successfully hydraulic mined in Western Canada and parts of Siberia it is realistic to believe that successful hydraulic mines can be designed and developed in the Western U.S.A. Particularly if the vast technological base that already exists is used to improve on other people's ideas, systems, methods and equipment.

Jan 1, 1983

By J. W. MacDonald

Review of equipment, performance, and shaft design plans including head-frames for sinking and forms for lining are given. Also included are comparative data for shafts of 11 x20 ft and 193/4 x 30 ft with 756 and 666-ft depths, respectively. Advantage from curtain wall installation with "slip forms" which warrant consideration for normal lining are outlined. A preliminary review is also made of "chemical grouting" to stop water inflow leakage with Halliburton equipment and service. Two coal mine shafts recently completed in Franklin County, Ill., afford experience and accomplishment to warrant review. These shafts provide access to a tract with a potential recovery of one hundred million tons. This work provided the initial sinking by other than a contractor's organization since 1918. Four additional shafts required during the interim were sunk under contract arrangement with others. Supervisory contact and inspection afforded experience to govern planning and conduct of the recent work. TEST DRILLING Core test holes were drilled within each of the two shaft locations. Four additional cable tool holes were drilled on a radius of 700 ft from the shaft bottom to determine the coal seam elevations and govern the underground layout plans for each shaft. A graphic log of the hoist shaft test drillhole is shown by Fig. 1. A very soft sandstone was found at a depth of 16 ft. Cored recovery of the sandstone proved much weaker than the overlying compacted sand secured with coring facilities for soil recovery. Gradation from the very soft sandstone to fairly hard material occurred with the next 14 ft, extending to a depth of 30 ft. The weak character within the upper portion entailed need of adequate protection when sinking as described later. A part of the sandstone provided sufficient porosity and permeability to warrant further investigation. Adjacent cable tool drilling for temporary water supply disclosed inflow was limited to 2 gpm with a depth of 40 ft. It was increased to 12 gpm during the next 50 ft of drilling and occasioned subsequent precaution when sinking. General arrangement of facilities for sinking the hoist shaft is shown by Fig. 2. An available steel frame building was used to accommodate the hoist, compressor, shop, and shower or change room. The stiff leg derrick with 90-ft length of boom permitted removal of forms from the wood shop to the storage area or delivery within the shaft. Reinforcing steel and other needs were similarly handled, in addition to headframe erection. The headframe was placed over one end of the shaft to enable passage of forms for lining through the adjacent half next to the stiff leg derrick. The steel headframe as shown by Fig. 3 was fabricated locally. Side anchored cables from the

Jan 1, 1961