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By Mingyang Li, Yan Lv, Xiaolong Ma, Xudong Gao, Jie Zhao, Yingyi Zhang

The reduction process of pre-oxidized ilmenite concentrate powder in 30%CO–70%N2 atmosphere was characterized by thermogravimetric and differential thermogravimetric (TG-DTG) analysis system at the temperature from 1073 to1223 K. The isothermal reduction results show that the reduction process is divided into three stages and the corresponding apparent activation energies are obtained by iso-conversional method and model-fitting method, respectively. For the first stage, the conversion degree increases sharply with increasing time, and the reduction process is controlled by the random nucleation and subsequent growth model (A2 model). For the second stage, the conversion degree increases slowly with increasing time, and the reduction process is controlled by the diffusion of carbon monoxide in the reduced layer (D1 model). For the third stage, the reduction processes at different temperatures are controlled by the diffusion of carbon monoxide in the reduced layer (1073 K and D1 model), phase boundary chemical reaction (1123 K and R2 model), random nucleation and subsequent growth (1173 to 1223 K, A2, and A3 models), respectively. For the whole reduction process, the apparent activation energies obtained by iso-conversional method and model-fitting method are 71.72 and 31.92 kJ mol−1 , respectively

By Corby G. Anderson, Sheikh Abdul Rezan Sheikh Abdul Hamid, Sanjith Udayakumar, Ahmad Fauzi Mohd Noor, Teuku Andika Rama Putra

Chemical and mineralogical characterization of Malaysian monazite, a phosphate mineral, bearing rare earth elements separated from the tin tailings originated from Ipoh, Perak, Malaysia, was performed in this paper. The study aims to collect detailed information on the chemical composition, crystal phases, and microstructure of the mineral monazite concentrate that would aid to optimize the subsequent hydrometallurgical processes for high-efficient separation of thorium and other associated rare earth elements. A systematic characterization study of the concentrate was conducted using techniques such as optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). These techniques analyzed the morphological details on the surface, elemental analysis, and mineral association assessment and identified the surface functionalization groups. The bulk composition and the mineral phases in which the elements are present were studied by wavelength-dispersive X-ray fluorescence (WD-XRF) and X-ray diffraction (XRD) studies respectively. The XRF analysis confirmed the presence of Ce, La, Nd, Pr, and Y (rare earth oxides: REO’s ~ 60 wt.%) while thorium dioxide (ThO2) accounted for 7 wt.% of the total composition. Traces of Ca, K, Al, Fe, Ti, and Mn were also confirmed by SEM elemental mapping. The XRD results confirmed that the concentrate was primarily composed of monazite (Ce, La, Nd, Th (PO4)) along with minor impurity phases of quartz. Automated mineralogical analysis was used as a confirmatory tool to corroborate the preliminary evidences. Based on the particle size distribution analysis supported by SEM, the majority of monazite grains were found to be present in the size range of 170–210 μm. Strong bands of PO4 and SiO4 were observed in the IR spectra corresponding to the phospho-silicate matrix of the REE mineral.

By R. G. Sinclair, E. Sangine, S. M. Fortier, J. Brainard, K. Stone

"The U.S. Geological Survey and Natural Resources Canada conducted a study on the net import reliance of each North American country, and the impact of North American trade on the net import reliance of 12 nonfuel mineral commodities that are associated with advanced technology products: cadmium, cobalt, gallium, germanium, graphite, indium, lithium, nickel, rare earth elements, selenium, silver and tellurium. The combined results for North America, using 2014 data, showed greatly reduced net import reliance for nearly all of the commodities evaluated, which is largely the result of pooling the resources of production and recovery in Canada and Mexico of materials that are consumed in the United States. This study highlights the mitigation of potential supply risk for critical materials that results from trade within the North American trade bloc. IntroductionMultiple metrics and definitions exist for what constitutes a critical material, but there is broad acknowledgment that a mineral commodity may be considered critical if, among other factors, its production is geographically concentrated, if it has few or no substitutes, or if the country of origin is politically unstable. Numerous governmental and independent researchers have proposed methods of investigating criticality, with differing priorities such as economic resilience or strategic military supplies (European Commission, 2014; Graedel et al., 2015; U.S. National Science and Technology Council Subcommittee on Critical and Strategic Mineral Supply Chains, 2016). While criticality really depends on who is asking the question, and despite the differing priorities, there are several commodities that are commonly found to be of concern. In particular, some critical or potentially critical materials are used increasingly in advanced technologies, or they have complicated supply chains because they are coproduced or are produced in controlled markets.Commodities for which imports are required to satisfy domestic demand are those for which the importing country is net import reliant. Net import reliance (NIR) in this study is calculated as the amount of imported material, including changes in stockpiles, minus exports and is expressed as a percentage of domestic consumption:"

Jan 7, 2018

By L. C. Lang

INTRODUCTION The introduction of 165-mm (61/z-in.) holes to underground mining operations has made possible the application of Canadian Industries Ltd's (CIL) vertical crater retreat (VCR) mining method, illustrated in the accompanying sketches. This unique and revolutionary new application of spherical charge technology (see the Appendix), when applied to primary stopes and pillar recovery, eliminates raise boring, slot cutting, and dilu¬tion of ore by backfill; greatly improves fragmentation; reduces labor and time requirements; eliminates uphole drilling and blasting; and minimizes or completely elimi¬nates damages by blasts to the walls and retreating backs of the stope or pillar. If vertical large diameter holes are drilled on a designed pattern from a cut over a stope or pillar to bottom in the back of the undercut, and spherical charges of explosives are placed within these holes at the calculated optimum distance from the back of the undercut and detonated, a vertical thickness of ore will be blasted downwards into the previously mined area. Repeating this loading and blasting procedure, min¬ing of the stope or pillar retreats in the form of horizontal slices in a vertical upwards direction until the top sill is blasted and the mining of a stope or pillar is completed. The VCR method is also applicable to drop raises and has the potential to replace all other raising methods under most circumstances. PILLAR RECOVERY Levack Mine Inco Metals Co., Ontario Div., provided the first opportunity for the method in pillar recovery. The Levack mine's high grade ore pillar No. 4800 on the 975-m (3200-ft) level was used for the production¬scale experiment (Figs. 1 to 3). The pillar was about 49 m (160 ft) long, 6 m (20 ft) wide, and 20 to 26 m (65 to 85 ft) high. The mined area on both sides of the pillar was backfilled with a 1:30 cement:sand mixture. The pillar was removed in two phases. In phase 1, the standard uphole method was used to blast down the 18-m (60-ft) long section of waste from the bottom of the ore into the undercut. From the pillar's top sill, 165-mm (61/a-in.) holes were drilled downward into the pillar, and by measuring the depth of the holes, the results of the uphole blast were determined and roof line 1 was established. The bottom of each hole was plugged, then filled with sand to place the center of gravity of each spherical charge (loaded from the top sill) at a predetermined optimum distance from the horizontal free surface. The charges were then detonated. After detonation, both draw drifts were full of extremely well-broken material. The depth of each hole was measured again, and the plot of these depths re¬sulted in roof line 2. The same blasting procedure was repeated and the resultant new back elevation was marked by roof line 3. The poor results of the initial uphole blast at one location (notice the peak in area 1) appeared to influ¬ence the subsequent new backs. A third blast success¬fully evened the back, and resulted in roof line 4. An unblasted slab averaging 6.3 m (20.9 ft) thick remained below the pillar's top elevation as the final sill. In all three spherical charge blasts fragmentation of the blasted material was extremely fine. The backfill was fully exposed on both sides of the now-blasted pillar. The backfill remained undamaged and the ore was not diluted by sand. The remnants of all the 165-mm (61/2 -in.) holes remained clean and undamaged, and the holes had well-defined bottoms that could be easily measured and plugged. Each blast took down a 3.9 to 4.2-m (13 to 14-ft) thick horizontal slab of ore. Productivity was three times greater than that of the previously practiced cut-and-fill method. Since this was the first such experiment, blasting the remaining 6-m (20-ft) thick final slab was the sub¬ject of some deliberation. If the described method was repeated, we could have ended up with a 1.8-m (6-ft) thick sill unsafe to work on. It was therefore decided to blast the whole sill using two spherical charges prop¬erly placed in each hole, but with the application of

Jan 1, 1982

By Fernando Jorge Dick

Artificial sulphides have been produced on the surfaces of heavy metal-oxide, minerals at elevated temperatures (1) and these sulphides gave consistently similar flotation characteristics as the respective natural sulphides. In the case of tin, the only natural tin sulphide known is herzembergite (SnS) which is found only in minor quantities, and its flotation behavior is not known. Balberyszki, Dorenfeld, and Carmi reported (2) tests with artificial tin oxide and pure cassiterite treated with hydrogen sulphide at temperatures above 750oc. They confirmed that the product could be floated in acid pulps. However, iron sulphides derived from pyrite, limonite, and hematite which are generally the major impurities in tin bearing ores could not be separated from tin sulphides under the conditions used by previous investigators. As a practical matter, if complex tin ores or complex low grade tin concentrates are to be treated by this process, it is necessary to be able to separate sulphidized cassiterite from other sulphidized minerals in the feed. The major metallic minerals, by weight, in complex tin ores are the iron minerals--pyrite, hematite, limonite, magnetite and pyrrhotite. These minerals become (or remain) sulphidized during the sulphidization process.

Jan 1, 1978

By W. C. Meyer

The concept of using powdered coal-in-oil-mixtures (COM) as a composite fuel to conserve oil resources and relieve import supply problems is being vigorously promoted by the Department of Energy via the sponsoring of various demonstration units (1). The idea of COM as a useful alternative fuel has been explored on and off for over 100 years (2). The approach must be capable of grinding, mixing, storing, and combusting COM with presumably only minor equipment changes on oil-fired boilers. DOE estimates that 56 000 m3 of oil (350 000 barrels) could be spared daily if a 50-50 COM was used to generate electricity. Of course, the ability of COM suppliers to prepare and deliver a stable suspension of COM at reasonable economic costs must be achieved if the concept is to be successful. This report reviews the various methods used to attain stable coal-oil mixtures. Various physical-chemical principles associated with each method of stabilization are also discussed.

Jan 1, 1981

By Peter Zhang, Mark Van Dyke, Ted Klemetti, Morgan Sears

Room-and-pillar mining is a mining method used in the United States to extract coal from underground, and pillar recovery is widely practiced for maximizing coal recovery and mining economics. Under certain conditions, room-and-pillar mining can create high stresses in coal pillars resulting in a coal outburst. These outbursts represent one of the more severe safety hazards in underground coal mines, potentially causing injuries and fatalities. Over the past ten years, coal outbursts have resulted in three fatalities in U.S. room-and-pillar mines. Though coal outbursts generally occur under deep cover, they are more likely to occur during pillar recovery and under multiple-seam mining conditions. Coal outbursts are generally associated with strong roof and floor and heavy loading of coal pillars, but it is difficult to predict whether, where, and when they will occur. In this respect, risk management provides a proactive tool to prevent coal outbursts in room-and-pillar mining by identifying mining areas with high risk of outburst and mitigating the risk accordingly.

Apr 26, 2022

By F. N. Siddiquie, Mohd Shaif, Rajiullah Khan, Juned Alam

Manganese ore bodies of Banswara Mn belt were classified into stratiform and stratabound types, based on their mode of occurrence, distribution, and their chemical characters. These ore bodies generally composed of braunite, pyrolusite, cryptomelane/ psilomelane, wad, etc. The stratiform-type Mn ore bodies are conformable with the associated host rocks (Mn phyllite, etc.) and occurred in the form of layers, bands, etc., which are variable in their shape and size. These ore bodies are also strongly folded with the enclosing host rocks. The others, which are stratabound-type Mn ore bodies, also showed an intimate association with the associated host rocks. These types of ore bodies occurred in thin layers, pockets, lenses, stringers, etc. The classified ore bodies are confined with Kalinjara formation of Aravalli Supergroup of Paleoproterozoic age. The ore bodies are structurally controlled and well associated with phyllite, schist, limestone, quartzite, etc. The stratiform-type ore bodies constitute a marginal to low Mn grade and are also characterized by lower Mn content (26.19–39.24%) along with the Mn/Fe ratio of 7.16–12.23, while the stratabound-type Mn ore bodies are rich in Mn (35.92–49.64%) along with the higher Mn/Fe ratio of 14.15–23.97. However, the poor Mn grade along with high siliceous impurities of Banswara Mn deposits is subjected to them for intermittent mining activities in the past and, consequently, did not attract the scientific and industrial community for the evaluation of these resources. Therefore, the authors attempted this study in a scientific and systematic manner (mode of occurrence/distribution and possible methods for evaluation/exploration) to evaluate the potential of existed and newer Mn deposit resources in the Banswara Mn belt. The whole findings would be very much helpful for exploration/ mining geologist along with other concerned, to completely evaluate these Mn deposits in the future.

Aug 16, 2021

By J. M. Mutmansky

A number of previous publications have attempted to provide the practicing ventilation engineer with simple guidelines on the optimal velocity to be used in mine openings. Some of these velocities were meant to be used in metal mining operations and some were meant for coal mining. A careful review of these publications reveals that the optimal velocities were determined based upon assumptions that are not existent today. As a result, they are not suitable for use in a modern coal mine. This paper takes a new look at this problem and determines a statistical relationship for optimal velocity that can be applied under both current and future conditions. The analysis performed here is based upon the determination of the optimal velocity for coal mine entries under variations in power cost, mining cost differential, airway friction factor, time value of money, airway lifespan, and quantity of air carried. A total of 8400 different conditions were analyzed for optimal velocity using computer calculation of the capital and operating cost values. Using the individual values of the optimal velocity derived in the calculations, a linear regression equation was fitted to the data to relate the optimal velocity to the other six variables outlined above. This regression relationship allows the ventilation engineer to make an easy, rapid determination of the optimal velocity.

Jan 1, 1984

By E. A. Lauha

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike sub-district of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike sub-district, there are seven major deposits: Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the sub-district are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Barrick Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post and Deep Star occur both on Barrick and Newmont property.

Jan 1, 1993

By William H. Pelton

The presence of high-grade massive sulphides near York Harbour, Newfoundland has been known since the turn of the century. In the early 1900's a small, massive-sulphide deposit was worked by conventional hand methods and yielded about 100, 000 tons of high grade copper-zinc ore. Since that time, a number of mining companies have held options on the property and an exploration adit was driven along the fourth level of the original mine. Underground drilling revealed several additional massive sulphide lenses in the range of 10, 000 to 60, 000 tons (Fig. 1). The problem facing Long Lac Mineral Exploration Ltd. when they undertook an option on the property in 1969, was to outline any possible extensions to the known sulphide lenses which were outside the reach of underground drills and to search for new ore deposits which might double the known reserves into a feasible project for development. GEOLOGY AND PHYSICAL PROPERTIES: The geology is typical of many massive sulphide deposits within volcanic rocks in the Canadian Shield. The sulphide pods appear to occur along a complex andesite-basalt contact. Identification of the two volcanic types is difficult since they are almost the same colour. The most direct means of identification is by the slight difference in their magnetic susceptibilities. Pyrite, chalcopyrite and sphalerite are the main minerals in the sul¬phide lenses. The ore is massive, differing in density from the host rock by at least 1.0 gm/cc. There is little pyrrhotite or magnetite associated with the sulphides, so there is no appreciable difference in magnetic susceptibility between the sulphides and the basalt. Also, there is no alteration halo around

Jan 1, 1971

By J. D. Miller

The sedimentary western phosphate deposits of Idaho, Montana, Utah, and Wyoming tend to be calcareous and generally carry a significant amount of dolomite along with collophanite. In some cases, such as the Smokey Canyon Mine, Afton, Wyoming, the ore will also contain mudstone, and in this case the aluminosilicate minerals (clay, feldspar, etc.) together with some dolomite are floated from the collophanite in column flotation cells with an amine in order to meet product specifications (31 % P205) (Service et al.). In other cases, such as the SF Phosphates Limited Mine, Vernal, Utah, the ore is treated by traditional fatty acid flotation of the collophanite with mechanical flotation cells (Weber, 1986). Preliminary tests have now been conducted to evaluate air-sparged hydrocyclone (ASH) technology for the flotation of western phosphate ore. For this preliminary study, samples were taken from the hydrosizer overflow stream (18-21 % P205) at the SF Phosphates Limited Plant in Vernal, Utah for scavenger flotation testing with the 2-inch ASH system in laboratories at the University of Utah. Selected design and operating variables are being studied, and the initial results show that satisfactory separations can be achieved by high-capacity ASH flotation at appropriate operating conditions. For example, with single-stage ASH flotation 80% recovery can be obtained with a scavenger concentrate grade of about 26% P2O5. These results are comparable to, or better than, those obtained at SF plant operations with conventional flotation cells and suggest that ASH flotation technology can be used to good advantage in the phosphate industry. Of course, research should be continued to consider other process streams, optimize the separation efficiency, and evaluate larger diameter ASH units.

Jan 1, 1993

The 6th International Mine Ventilation Congress (IMVC) was held May 17-22,1997, in Pittsburgh, PA. This marked the second time that the IMVC was held in the United States. The first congress, organized in 1975 by the Mine Ventilation Society of South Africa, was held in Johannesburg. Since then, the meetings have been held every four or five years, with the 1979 meeting being held in Reno, NV. This was followed by Harrogot, England, in 1984; Brisbane, Australia, in 1988; and Johannesburg, South Africa, again in 1992. The IMVC provides an international forum in the field of mine ventilation for the purpose of sharing technology and experience. The meetings are attended by ventilation engineers, academics, consultants, government employees and vendors interested in mine ventilation. As was evident from this meeting, significant progress has been made in the field of mine ventilation. However, disasters continue to occur around the world and long-term health problems continue to affect workers. So there is a need for further improvements in ventilation technology. The highlight of the conference was the technical sessions in which more than 80 papers were presented by authors from more than 20 countries. In addition to the technical sessions, the conference featured field trips to a number of mine properties throughout the United States. Five short courses were offered on topics ranging from respirable-dust control to mine fires and explosions. The conference also featured a trade show. It exhibited the latest advances in ventilation equipment, computer application software, consulting and engineering services, and health and safety equipment.

Jan 1, 1997

By Jay F. Colinet

Coal workers’ pneumoconiosis (CWP), commonly known as black lung, is caused by the inhalation of respirable coal mine dust and is a disabling and potentially fatal lung disease with no cure. Historically, CWP has taken a tremendous human and financial toll in the US coal mining industry. Recent health surveillance data indicates that CWP continues to occur at elevated levels. Respirable coal dust exposure must be controlled to prevent the development of CWP. The Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH) conducts laboratory and mine-site research to identify control technologies that can be used to successfully reduce respirable dust levels. Various technologies, using multiple methods of control, can be applied in order to reduce dust levels. An overview ofCWP’s impact and a general methodology for controlling respirable dust in underground coal mines are discussed in this paper.

Jul 30, 2020

By David A. Heitman

The Buick Concentrator is a highly automated operation which utilizes a process control system for continuous monitoring and control. The process control system development, installation, and application to the concentrator grinding and flotation circuits are presented in this paper. The design and implementation of analog field sensing instrumentation, a continuous on-stream X-ray analyzer, grinding and classfication circuit controls, and a recent digital process control system utilizing a centralized computer are discussed. Emphasis is placed on the project planning and installation of the digital control system including a presentation of future plans for continuing application of computer control.

Jan 1, 1982

By S. Crewdson

Vertical hoisting of materials using hoists and skips is common in the Mining Industry. These systems have a number of drawbacks, one being limited hoisting capacity at medium depths. FKC-Lake Shore and Metso Flexowell have been developing and installing vertical belts for medium depth shaft applications for many years, progressively going deeper whilst increasing belt capacity. The latest development from Metso the Pocketlift® belt advances this technology allowing higher tonnages to be lifted from greater depths. The design, manufacture, installation and operational experience of a 1818 tonnes capacity, 273 meters vertical lift Pocketlift® system at the White County Coal Pattiki 2 mine is the subject of this work.

Jan 1, 2003

By John Newby, Ulf Gwildis, Ken Massé, Guillaume Roux

How to connect an effluent conveyance tunnel to riser shaft and diffuser arms of an outfall system is dictated by the ground conditions, which ideally include rock or soil strata of low permeability. Where such favorable conditions are beyond reach, both the complexity of designing and the risk of constructing this crucial system connection increase disproportionally. This paper describes the considerations that went into the approach of connecting a 5-m-diameter TBM drive with the in-river riser shaft of the Annacis Island WWTP New Outfall System in the highly permeable Fraser River sands at hydrostatic pressures exceeding 3 bar.

Jun 23, 2024

By P. O. Ripley

Into this tumultuous twentieth century, every second, two new babies are born. This is 5,412 per hour, and 130,000 per day. Relentlessly, consistently, alarmingly, they add to the more than three billion human beings who already inhabit the earth. Every tick of tier clock brings with it a problem child, the problem of another mouth to feed, another body to clothe, another human being for whom to provide. On the other hand, medical science has achieved a postponement of death, considerably past the period of a few years ago. Thus, life expectancy has been increased and world population has increased accordingly. Darwin (4) writing in 1962, suggests "It is curious how long the world is taking to perceive that we are living in what is a fantastically abnormal period of history, and one which must inevitably end soon, The first warning note of a possible population explosion was given by Malthus in 1799". He suggested that population increases geometrical while production increases only arithmetically and that soon we would not be able to feed the rapidly increasing population.

Jan 1, 1966

By Valérie J. Bertrand, Richard W. Lawrence, Marcos G. Monroy

Two cemented paste backfill (CPB) formulations containing pyritic tailings were leached in deionized water in flooded and alternating air-flooded environments and in a simulated acid rock drainage-type (ARD) solution. Scanning Electron Microscopy (SEM), solid phase chemistry and acid-base accounting measurements documented the weathering characteristics of the CPB samples. Short-term exposures of the portland-CPB samples preferentially dissolved the cement binder to a greater extent than slag-Portland CPB mistures. In all cases, the added neutralizing potential provided to backfill by cement was short-lived and insufficient to neutralize the acid generating potential of the mixture.

Jan 1, 2000

By Don S. McCoy, W. Joseoph Schlitt, Donald B. Swanson

Introduction Contract miners have long played an important role in the minerals industry. Historically, these were individuals who worked as underground miners and were paid by the ton or the day. These hardy types still ply their trade in the industry. However, today the term "contract miner" generally refers to an independent contractor who supplies the people and equipment needed to conduct surface mining operations for an owner or lease holder. At one time or another, contract miners have probably handled virtually every mineral commodity from sand, gravel, and stone quarrying to mining uranium and precious metal ores. In today's market, though, contract mining appears to be concentrated in just a few areas. These include precious metal mines, various types of solid fuel operations, and reclamation of abandoned mines. This article covers market areas, contract mining organizations and services, and their advantages and disadvantages. Gold and silver mines Although exact figures are not available, contract mining represents a significant element in the precious metals segment of US mining. For gold and silver, the growth in contract mining appears to be paralleling the overall growth in mining activity itself. Nevada is the largest gold producer in the US. The latest available data (1985) on open pit gold/ silver mines is summarized in Table 1 (Nevada Division of Mine Inspection, 1986). These figures show that contractors mined nearly half of the ore in 1985. Total tonnage mined, of course, was much higher for both owners and contractors. Assuming an average stripping ratio of 2.5 to 1, the total daily mining rate for the contractors was more than 145 kt (160,000 st). This translates into a contract mining rate of about 36 Mt/a (40 million stpy) based on 250 operating days a year. This approximate 50-50 split between owner and contractor also appears to hold for the future. Metals Economics Group (1987) published a survey of 51 short-range and 54 long-range precious metal projects being considered throughout the US. Contacts with owners, requests for proposals, and past corporate philosophies all suggest that about 55% of the open pit operations scheduled for the near-term will be contract mined. This represents an estimated 26 kt/d (28.5 stpd) of ore. A similar assessment of the long-term projects indicates that about 12 kt/d (13,000 stpd), or just under 50% of the open pit tonnage will be contract mined. There are several reasons why gold and silver represent such an attractive opportunity for contract miners. One is that many properties are owned or leased by individuals or partnerships that are essentially entrepreneurial. Many of these owners or lease holders have minimal mining experience. They must therefore either rely on contract mining organizations, sell an interest in the project to another mining company that will become the operator, or hire an experienced management team. For about the same reason, junior mining companies also represent good prospects for contracting. This is because most junior companies focus on exploration. They would prefer to spend their generally limited funds on drilling programs. Thus, they tend to minimize additional capital requirements by using contract miners or farming out the property to another mining company. Another good reason for using contract miners is the size of the deposit. Many properties are so small that their reserves will not support the capital expenditures

Jan 12, 1987