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By K. Norris

The Amax Gold Guanaco mine is located in the Atacama Desert, approximately 260 km southeast of Antofagasta, Chile. The 6,000 tpd leach operation produces approximately 90,000 oz of gold, and 360,000 oz of silver per year. Production began in 1987, and the operation has been managed by Amax Gold since 1992. The mine has been plagued in the past by high operating costs and low production. Several significant changes have been made to the operations which have resulted in lower costs and higher operating efficiencies. A review of these changes is presented herein.

Jan 1, 1997

By B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1993

By R. Grandori, L. Pellegrini

The construction of the La Joya hydropower plant (Costa Rica) was awarded by the Spanish power company, Union Fenosa, to the Italian Joint Venture formed by the companies SELI SpA and Ghella SpA. The project, located in a mountainous region of central Costa Rica, includes a 7.9-km-long head race tunnel having an excavation diameter of 6.18 m. A double-shielded TBM was selected to perform the tunnel excavation, which involved mainly volcanic rocks in variable but generally very weak conditions. The tunnel crossed long and continuous sections in completely weathered rock masses with no residual cohesion and with high water inflows. The paper describes and analyzes: The special methods adopted to overcome these sections with the TBM includ-ing face stabilization by chemical grout and foams as well small by-pass tunnels in the crown combined with TBM advance/support The grouting design and the grouting method that was implemented to meet the waterproof design specifications and restore the original groundwater level in the mountain The additional geological investigations performed to improve the knowledge of the rock mass in front of the TBM and the outcomes of these investigations The performance of the TBM in different ground conditions and on average along the entire tunnel Finally, the author’s comment about the possibility of implementing and improving the technologies experimented with in this project in future similar applications.

Jan 1, 2007

By H. N. Frock

The use of low-angle forward light scattering for measurement of particle size distribution has been described previously.1 Laboratory instrumentation using this technology is used routinely in operating plants for quality control and production control.2,3 Extension of the technique to on-line process monitoring and control has also been undertaken in several important areas. This paper will discuss the application of MICROTRAC R systems to the monitoring of particle size in wet slurry processes and dry powder grinding circuits. Examples of existing installations will be given with emphasis on performance and on-line reliability.

Jan 1, 1979

"It’s been 80 years since Charles Warman invented the iconic Warman slurry pump, a pump that revolutionized the mining industry and continues to push the boundaries of pump performance to this day.In honor of this legendary brand, Weir Minerals hosted an event at the end of May in Kalgoorlie, Western Australia. Throughout the evening, attendees relived Warman pumps’ history and gained an insight into some of the future innovations planned.“It was a privilege to share this special night with some of our key customers, past and present employees, and members of the Western Australian School of Mines,” said Ricardo Garib, divisional president of Weir Minerals. “Warman is one of our leading brands. It has truly shaped the mining industry over the past 80 years and is a product we are all very proud of. The Warman pump, invented to solve high wear issues in slurry pumping, created a thriving industrial business that is now the cornerstone of Weir Minerals with more than 8,000 people, and more than 150 manufacturing and service centers across the globe.”Always inventingCharles Warman invented the Warman slurry pump in Kalgoorlie in 1938. It was a hardwearing slurry pump that used replaceable liners and a replaceable impeller, something that had never been done before.“Charles Warman was a visionary and an innovator. The use of rubber lining in the pump was groundbreaking as it reduced total ownership costs, was safer to handle and offered extended wear life in many abrasive slurry applications. It is a great example of solving customer problems with material science, and is still taught in universities today,” said Marcus Lane, global product manager for centrifugal pumps at Weir Minerals.It was quickly adopted throughout the goldfields in Western Australia and by the 1950s, as customer demand rose, Warman expanded his business by opening offices in Sydney and Perth.During the 1960s the rapid growth of the business continued with manufacturing and sales outlets established around the world. The Warman Series ‘A’ pump was accepted and became a world leader in its field. Further work on the Warman AH pump resulted in the development of interchangeable metal and rubber wearing components."

Jan 9, 2018

By Mirjana Boskovic

LKAB’s Kiirunavaara Mine is a sublevel caving iron-ore mine located above the polar circle in northern Sweden. The mine has been proclaimed seismically active since 2008 after a magnitude 3 seismic event, according to Swedish National Seismic Network (SNSN). At that time the Kiruna Mine did not have mine-wide seismic system. Since then, the Kiruna Mine experienced several damaging seismic events of which the largest one on the May 18, 2020. The magnitude, based on the moment tensor inversion results on data from the SNSN as well as seismic stations in Finland and Norway, is estimated to 4.2 ± 0.2 moment magnitude. The seismic event on the May 18, 2020 was located in the middle of the one of the productions areas and caused the major damage in the mine, damaging several kilometres of drifts on six mining levels, some of them beyond the practical repair. These damages affected four of ten production areas on several levels, some more some less. Luckily, no person got injured from the seismic event and the very long aftershock series. An important part in the whole process after the seismic event was information flow and decision-making process. It was very important to keep workers and community informed as that contributed transparency of decision-making and decreased the speculations. Resuming the production in the damaged areas in the safe manner, very soon become main focus for the mine management. It was obvious that not only rehabilitation of the areas is needed to resume the production. It was A MUST to understand the factors behind the seismic event and its mechanism to be able to avoid same situation and prevent seismic event of similar size. Mine engineers had to think outside the box to find the solutions to ‘rescue’ every drift that they could to be able to make good enough base for continued mining of the area. The paper describes actions taken in a very complex process of recovering the area that we from the beginning thought need to be abandon. Seismological analyses of the event on May 18, 2020 and past activity in the area, damage mapping, detailed studies of structures and geology, numerical modelling as well as engineering judgement were used as base for all our decisions how to proceed in attempt to restore mining of the area heavily damaged by 4.2 moment magnitude seismic event, in a safe way.

Apr 26, 2022

By F. Warnaars

Historically, this area produced gold and silver from many well-known vein deposits, like Tayoltita, Topia, and San Jose de Gracia. Modern exploration identified three categories of deposits: 1) low grade porphyry golds in shallow level dacite porphyries; 2) batholith-related deposits; and 3) those formed in volcanic sequences of Late Cretaceous to Late Tertiary. At least four porphyry golds have been identified, of which Metates is best known. These are formed by and within daciteporphyries, associated hydrothermal breccias and sometimes within surrounding meta sediments. Their ages are from mid-Cretaceous to Early Tertiary. Precious metal deposits associated with batholiths occur as veins, contact haloes in meta sediments or volcanics, skarns, tectonic breccias, hydrothermal tourmaline breccias, dacite dikes or as disseminated or stockwork deposits such as La Fortuna.Several new gold discoveries were made in older EarlyTertiary Volcanic Sequences and in the younger Tertiary volcanics within prominent structures exceeding 3 to 5 km in lengths. Some of these are open-pittable but most have to be mined by underground methods.

Jan 1, 1999

By S. G. Gendler

The choice of ventilation schemes in the Northern Mujsky railway tunnel and definition of the nec-essary quantities of air ensuring regulated radiation conditions in the tunnel system has been accomplished. The influence of natural draught on the stability of tunnel ventilation has been estimated. The design of a portal venti-lation gate allowing minimal influence from natural factors is described. The dependence of pressure loss in the sliding ventilation gates on their spanning value of the vehicle tunnel section has been determined. The selection of parameters for an atmospheric air heating system in winter has been carried out. The operation regimes of air heaters, dependent on the temperature of atmospheric air, have been established.

Jan 1, 2009

By G. T. Homce

Most electric motor predictive maintenance methods have drawbacks that limit their effectiveness in the mining environment. The U.S. Bureau of Mines is developing an alternative approach to detect winding insulation breakdown in advance of complete motor failure. In order to evaluate the analysis algorithms necessary for this approach, the USBM has designed and installed a system to monitor 120 electric motors in a coal preparation plant. The computer-based experimental system continuously gathers, stores, and analyzes electrical parameters for each motor. The results are then correlated to data from conventional motor-maintenance methods and in-service failures to determine if the analysis algorithms can detect signs of insulation deterioration and impending failure. This paper describes system design and implementation. At this writing, however, installation is still underway, and field data analysis results are not yet available.

Jan 1, 1994

By D. A. Karvonen

Although the economy in the Province of Saskatchewan has historically been agriculturally oriented, a major new source of wealth has been realized through natural resources such as petroleum and natural gas, coal and uranium and since the 1960's - potash. Potash or potassium chloride, in the form in which it is presently produced in Saskatchewan is used primarily as fertilizer, a source of potassium, one of three essential elements required for healthy plant growth with about 5 percent of production sold to the chemical industry for use in such products as soap and liquid detergent, glass and ceramics, textiles and some pharmaceuticals. Saskatchewan is estimated to have approximately 40 percent of known world potash reserves and its ten active mines account for some 25% of annual world production. The development of this resource was recognized to be important to the development of Saskathcewan. In an effort to guarantee a fair and lasting economic benefit to the Province of Saskatchewan the Potash Corporation of Saskatchewan (PCS) was created on February 4, 1975 through an Order-in-Council under the Crown Corporation's Act and later on April 1, 1976, the Potash Corporation Act provided for its continuation. PCS was given the mandate to acquire ownership of a significant portion of the potash mining capacity in Saskatchewan and to establish an organization capable of operating the facilities, marketing the product and conducting all of the other activities necessary for a successful corporation competing in the world potash industry.

Jan 1, 1983

By Mustafa Kumral, Samer Hmoud

Effective management of ore loss and dilution is essential for successful grade control and short-term mine planning due to their significant impact on the economic, environmental, and technical aspects of open-pit mining operations. Factors influencing ore loss and dilution fall into two categories: (i) controllable factors like mine equipment selectivity and blast design and (ii) uncontrollable factors such as spatial heterogeneity of ore and waste blocks on a bench. This paper focuses on the second category by applying spatial entropy concept to capture heterogeneity at the scale of selective mining units. In this paper, global spatial entropy is used to assess the impact of spatial heterogeneity between ore and waste blocks on the magnitude of ore loss and dilution, while the local spatial entropy can guide the allocation of blast movement monitoring balls pre-blast. High values of the global spatial entropy indicate increasing potential of ore loss and dilution, which reduce profit. Furthermore, the study investigates the relationship between spatial entropy, cut-off grades, blast movement, dig-limits optimization model running time, and profit through a number of case studies. The results show that changes in cut-off grade and blast movement can significantly affect spatial entropy post-blasting and increase ore loss, dilution, and profit reduction, revealing the need for controlled blasting at specific bench sections. Additionally, the results demonstrate an exponential increase in profit reduction due to ore loss and dilution with a rising global spatial entropy.

Nov 28, 2023

By J. C. Irvine

Meramec Mining Company, a joint venture by Bethlehem Steel Corporation and St. Joe Minerals Corporation, is engaged in the mining, concentrating, and pelletizing of iron ore from the Pea Ridge Mine located near Sullivan, Missouri, about 70 miles southwest of St. Louis. The orebody was delineated in the mid-1950's by St. Joe during an exploration program to discover new lead orebodies. An airborne magnetometer survey which was run by the U. S. Geological Survey, the Missouri Geological Survey, and several min¬ing companies was published in 1950 and showed an anomaly in the Pea Ridge area. Test holes drilled in 1953 and 1954 revealed the presence of a large orebody of probable commercial significance; additional drilling in 1956 and 1957 provided confirmation of this. Meramec Mining Company was incorporated in 1957 and shaft sinking began in the latter part of that year. The Pea Ridge orebody lies under about 1300 feet of sediments. It is tabular, about 2600 feet long and up to 600 feet thick, and lies in an approximate east-west delineation. The orebody dips about 800S and is of unknown depth. The ore is primarily high grade magnetite with smaller zones of specular hematite, The Pre-cambrian wall rock is rhyolite porphyry. The mine is serviced through two concrete-lined shafts, 19 feet 1 inch in diameter and 2500 feet deep. No. 1 shaft, equipped with an "A" type head-

Jan 1, 1972

By George R. Stephans

The Climax Mine is a panel caving mine which has had a long history of incidents of severe ground control problems. The nature of the ore deposit, which lends itself to the caving meth- of of production, a1 so makes the mine susceptible to large scale stress concentrations which are referred to as ?weight? problems. These problems have increased with increased production and also with expansion to deeper mine levels. During the past twenty years the mine has had to learn to cope with these problems in order to remain in operation. A number of practical guidelines and useful techniques have emerged from these efforts. The purpose of this paper is to share a few of these ideas. The Mine is located near Leadville, Colorado on the continental divide at an elevation of 3450 meters. The ore body is a large low grade deposit of disseminated molybdenum sulfide. It measures about 1200 to 1600 meters in diameter and it had an original depth of about 660 mters. The Mine has been in operation since 1918 and the massive nature of the ore body together with its blocky, highly fractured condition made it natural for the caving system to have been adopted for production at an early date. Open pit mining was started in 1973. The total plant has a capacity of more than 50 thousand tons per day, and more than 400 million tons of reserves at an average grade of 0.310 percent molybdenum disulfide remain to be produced.

Jan 1, 1982

By James A. Clum

The shift to lower grade iron ores, e.g., magnetic taconites, resulted in a shift towards agglomeration practices which could effectively deal with the fine particle sizes generated in the liberation and concentration processes. If the iron bearing particles are not extremely fine, e.g., -1/2 in + 100 mesh, sintering is an adequate means of agglomeration.(1) For the more dispersed ores which result in fine concentrates (more than 80%,-325 mesh), the fine particles must be agglomerated by mechanical means before final hardening, e.g., pelletizing.(1) In the pelletizing process, the essentially mechanical step of balling is extremely critical since the strength of the pre-fired pellet determines the firing conditions. The ability of the proper amount of moisture to hold together a ball of the very fine ore concentrate particles has long been recognized. It is a charac¬teristic of the reaction at the interface between the ionic solid of the ore concentrate and the polar water phase which overlays the solids. The strength in such moisture laden balls, the green strength, is a strong function of the water content (Figure 1) and thus deteriorates rapidly for either a small excess or a small deficiency of moisture. For purposes of commercial practice, the control of green ball handling properties by accurate control of ball moisture is too demanding. Moreover, as the ball is heated towards its hardening tempera¬ture, e.g., 1300'C, there is a substantial drying reaction which would lead to such a low dry strength of the ball that it would not support its own weight much less the weight of other balls in a firing furnace.

Jan 1, 1976

By T. Harris

Exports of crude gypsum from Mexico currently comprise about 60% of all domestic shipments, and about 25% of the imported material consumed in the U.S. wallboard industry. However, of growing importance are the domestic markets for calcined gypsum in Mexico including building plasters and wallboard, which account for 55% of the internal demand for natural mined material. This paper will examine the current trends in the production and trade of natural mined gypsum in Mexico and North America and the opportunities and threats that are facing existing and new suppliers in this changing market.

Jan 1, 1996

By J. L. Kearns

The importance of optimizing equipment replacement decisions becomes more critical each year due to the rising costs of buying new equipment versus maintaining old equipment. Replacing equipment when it is physically worn out, or replacing it too soon or too late relative to its Economic Life (when it is economically worn out), is very costly. After extensive literature review and research, Kennecott has developed its Equipment Replacement Guide (ERG) system which identifies, evaluates, and justifies the replacement of uneconomical equipment. The system considers such critical factors as inflation, decreasing work capability, increasing maintenance/repair and operating costs, taxes, time value of money, return on investment, salvage value, and investment tax credit. These factors are used in a system of equations which balance the costs of new equipment against the total operating costs of old equipment. The solution of the equations determines the Economic Life of equipment. Replacement of equipment at the determined Economic Life will earn the specified, required return on investment that is used in the calculation of the Economic Life.

Jan 1, 1979

By Manfred G. Raschke

INTRODUCTION In the past decade, the international coal trade has been undergoing a period of gradual change. This change will continue through the remainder of this century until by the year 2000 the international coal industry will look very different from the industry which existed in the early 1970's. The industry which will emerge from the thirty year period of change (1970-2000) will be different in many ways. -The volumes of coal transported will be much larger. - The primary type of coal traded will be steam coal rather than metallurgical coal. - A much broader group of countries will be participating in the trade both as suppliers and as consumers. - The trade will be dominated by a relatively small number of large producing and trading companies. - The coal mined for international shipment will be primarily surface- mined. – The United States will play a decreasingly important role in international coal trade. In the course of this paper I propose to address three questions which are crucial to the formulation of an understanding of the changes outlined above : (1) Which supplier nations will be most successful in the international metallurgical and steam coal trade in the next decade and a half? (2) What emerging trends will shape the international coal trade in the 1980's and 19901s? (3) Where are U.S. producers likely to fit in this scheme of things? As a background to my remarks, I should note that what follows is based on five years of work in a consulting capacity on coal supply and demand issues worldwide. Although in the course of this work I have had occasion to develop mining and transportation cost figures for all of the countries discussed below--both my own and those obtained from coal producers--it is apparent that success in the marketplace can be determined in some instances by considerations other than costs. Nevertheless, my comments today about international competitiveness will be dominated by cost considerations; there are, after all, not many markets that reward the high-cost producer with success. Let us begin by establishing some criteria for success in the international coal market and then compare some of the producer nations to some of these criteria. The criteria are: - Low delivered cost, - Good quality coal, - The producer's partnership in a joint mining venture with an importer or a consumer of coal, - The producer's international business orientation and commitment to penetrating the market, - The producer's reliability as a supplier, and - Political pressure exerted by the producing country on consumers.

Jan 1, 1986

By D. J. Benton, S. Finley, D. T. Orr, A. J. Chambers, M. A. Stepan

"Corrosion of ground support can lead to falls of ground that pose a significant risk to miner safety. To address this problem, the National Institute for Occupational Safety and Health (NIOSH) is investigating corrosion at the Hecla Mining Company’s Greens Creek Mine, located near Juneau, Alaska, USA. Field studies have used photogrammetry surveys to document welded-wire mesh corrosion, and laboratory studies at NIOSH’s Spokane Mining Research Division (SMRD) have investigated the effects of corrosion on ground support integrity. Findings show that (1) corrosion monitoring through photogrammetric methods may be effective for qualitative measurements of welded-wire mesh corrosion, and (2) there is a relationship between loss of load-bearing capacity and the diameter loss due to corrosion in welded-wire mesh. Photogrammetry results thus far have measured an apparent bulking of the corroded welded-wire mesh, and preliminary laboratory tests have investigated the relationship between the larger bulked and effective wire diameter. If this relationship is verified, these results may indicate that photogrammetry, when combined with the models produced in laboratory tests, could offer a means of monitoring corrosion levels, as well as rock rib deformation. INTRODUCTION Reducing the number of rock fall injuries and fatalities is an important part of the mission of the National Institute for Occupational Safety and Health (NIOSH) Spokane Mining Research Division (SMRD). Ground control using support systems to protect miners from rock falls is one of the oldest mining sciences, and considerable research has led to a variety of modern tools and methods in use today. Among these tools are rock bolts and welded-wire mesh, which are made from increasingly higher-strength steel grades to meet the increasingly demanding requirements of underground mines [1]. However, the benefits of these higher-quality support elements may be negated in corrosive mining environments. A better understanding of how corrosion affects the support capacity of ground support systems will assist engineers in determining when an opening is at a greater risk of falls of ground. Accelerated corrosion has been occurring in some areas of the Hecla Mining Company’s Greens Creek Mine near Juneau, Alaska, USA. Corrosion of ground support has resulted in two falls of ground occurring between April 2015 and March 2016. While these falls of ground did not injure any personnel, mine management recognized the high risk to miner safety and responded by actively undertaking a ground support rehabilitation program. Rehabilitation measures include the installation of both galvanized and coated, corrosion-resistant bolts and welded-wire mesh, depending on local conditions."

Jan 1, 2017

By Minor S. Jameson

This paper presents considerations in support of a U. S. oil import policy more restrictive than the present Government import program. A lower level of imports and greater long-range stability in the relationship between imports and domestic production are recommended. Reference is made to increasing world-wide surpluses of oil and wide disparities in foreign vs. domestic costs. Resulting economic forces are held responsible for the increase in imports (excluding residual fuel oil) of almost 300 percent and the change in ratio to domestic crude production from 5.4 percent to 13.9 percent during the period 1946-1956 prior to import restrictions. It is pointed out that these imports continued to increase during the years of import restrictions to a ratio of 17.3 percent of domestic production in 1961. Data are presented showing that increasing oil markets outside the United States provide an outlet' for more than 80 percent of total foreign production, with 90 percent of the increase in foreign production going to foreign markets. Attention is called to the fact that, if there had been no increase in United States oil imports during the past five years, foreign production would have increased by 45 percent in contrast to a static level of domestic crude oil production. The need for a less restrictive import policy in the interest of encouraging foreign oil development, therefore, is questioned. Declines since 1956 in the range of 30 percent in domestic exploratory crews, rotary rig activity and wildcat well completions in the United States are cited, together with a decrease of 9 percent in industry employment and increases of 9 to 18 percent in elements of cost. Recognizing that factors other than imports affect the domestic industry, it is concluded that continuing declines in the vigor, capabilities and competitive structure of the domestic industry can be expected unless further import restrictions are imposed. The public interest in assuring adequate domestic supplies is considered in the light of the role of oil and gas as a source of almost three-fourths of U. S. energy requirements and the economic benefits from petroleum production with a value exceeding the combined value of all other minerals in the United States.

Jan 1, 1962

By R. E. Hamilton

Automation is a word whose meaning has been broadened by popular usage to include any labor saving device. We with restrict our usage to the replacement of human judgement by instrumental measurement and mathematical analysis in the control of industrial processes. Mineral concentration is an area which has resisted automation because of the great difficulty in developing measuring instruments which can exist in the rugged environment and can measure useful properties with acceptable accuracy. This is not the only factor limiting progress, but until recently it has been of over-whelming importance. The development of on-stream X-ray analysers, magnetic flowmeters and nuclear density meters for mineral slurries has eliminated this obvious barrier and is enabling us to locate and attack the less obvious problems which still limit our ability to automate concentrators. If we examine the history of automation in industries which are highly automated we find that it has usually gone through three distinct phases. The first phase has been regulation. This is the simplest form of control and involves manipulating some variable whose value is of no importance in order to maintain the value of some other variable which is important at a constant specified value in spite of disturbances which may occur in other variables which affect it. A simple example is the use of a control valve to maintain a constant flow of fluid in a line in spite of changes in pressure in the vessels at the ends of the line. The position of the valve stem is of no consequence, as long as it is within its operating range. Unfortunately we soon run out of variables which can be

Jan 1, 1971