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By Marcel Laflamme, Sebastián Ibarra‑Gutiérrez

Improvement on controlling the stope limits has enabled the assessment of technical performance in several underground mining operations. Technical performance, integrated to stope geotechnical and geomorphological parameters, constitutes the basis which guides mining engineers in the Mineral Reserves Estimation process. Moreover, there are established definitions to report this information in Canada, incorporated in NI 43–101, which stipulates that “A Mineral Reserve includes diluting materials and allowances for losses that may occur when the material is mined” [1]. However, some loopholes have been identified regarding practical standards followed to specify the way to include and report ore losses when the lost material was blasted and must be left behind unrecovered inside the stope. In fact, general efforts to estimate and quantify the negative effects of operational ore losses only consider under-break ore loss. However, mining engineers frequently confront situations requesting the anticipated closure of a stope. Therefore, reconciliation process should reflect the amount of unrecovered Mineral Reserve. This work presents a discussion of possible practices to integrate adequately operational ore losses consisting of blasted but not recovered material and focuses on how different approaches regarding the material constitution could severely affect the stope technical performance interpretation.

Aug 9, 2021

By P. C. Kapur

The kinetics of green pelletization in a laboratory balling drum have been studied, using pulverized limestone as a model system. The growth characteristics of green pellets were found to be extremely sensitive to the moisture content of the material. Empirical kinetic equations, which incorporate a function of specific surface of the pellets as the criterion for growth potential, have been found to describe growth in a nucleation region and in a ball growth region. The rate constants in the kinetic equations are strongly dependent on the moisture content of the material being pelletized. Size distributions of the halls at different stages of pelletizing are also discussed.

Jan 1, 1965

By Robert M. Dreyer

In an industrialized nation, as the process of industrialization continues, the ratio of the value of production of non-metallic to metallic minerals normally increases gradually over a period of years. For example, in the United States, the ratio of the value of production of non-metals to metals now is approximately two-to-one. Those of us who come from California like to think that we inherit the mantle of the old hard-rock miner, but the truth of the matter is that, in California, of the total value of mineral production exclusive of fuels, 97% comes from non-metallic - industrial - minerals. Since the industrial minerals furnish a principal source of raw materials for the construction and chemical processing industries and since these two industries, in industrialized nations, generally increase directly with increasing population, the future of industrial mineral production both in the United States and throughout the world is indeed bright. Because of the importance of industrial mineral production, it often surprises those of us in the industrial mineral industry to find that industrial minerals are poorly understood by many of our colleagues in the mining industry. I think that one reason for this comprehension of the industrial mineral industry is that the education of both geologists and mining engineers still markedly emphasizes exploitation of the metals.

Jan 1, 1964

By B. E. Penrod

The main constituents of flat glass are the eight commonest elements of the earth's crust. Five of these, silicon, sodium, calcium, magnesium and oxygen are essential. Two more, Aluminum and potassium have beneficial properties. For colorless glasses iron is undesirable, in standard clear glasses a small amount of iron is tolerable, while for most tinted glasses iron is essential. These elements are present in glass as oxides and because they are so common there is no foreseeable resource shortage. The availability of supplies of materials at particular sites at prices which enable a glass manufacturer to be competitive may be another matter. In this paper it is intended to provide a historical perspective to the current situation, to contrast some of the traditional North American and European practices, and to progressively review some of the driving forces for future change and to attempt to assess their effects upon both raw material supplier and consumer.

Jan 1, 1994

By Richard M. Tinlin

The mining industry needs to assure compliance with the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500). Congress has enacted this legislation with the intent of preventing, reducing, and eliminating pollution of the nation' s surface and groundwaters. Recognized sources of pollution such as seepage from tailings ponds, waste dumps, and contaminated effluent from mine dewatering operations pose a serious threat to adjacent groundwaters. In addition, technological innovations being implemented by the industry such as in situ leaching of low grade ore deposits may also lead to ground- water contamination. An adequate monitoring methodology designed to meet the needs of the mining industry is needed. Monitoring and control methodology devised for other man- caused sources of ground- water pollution - e. g., landfills - offer considerable promise for adaptation to the problem. The prediction of deleterious effects on groundwater quality usually requires extensive geohydrological data in addition to a thorough analysis of the mining activity that is underway or projected. If the avail- able data are adequate, mathematical models of surface and groundwater flow can be constructed that will help to predict effects on water quality. Data are inadequate to allow a realistic interpretation of pollution potentials. These data can be supplemented by computer simulation as a method to explore a number of possible environmental effects and also to develop a minimum-cost approach to identifying and gathering the additional necessary supporting data. Incorrect assessment of the important environmental considerations may, in many instances, prove to be the weakest link in analyzing the financial feasibility of a mining operation.

Jan 1, 1973

By C. Clark, J. Johnson, M. Stepan

"Shotcrete and mesh are often installed to control ground deformation, falls and ejection between bolts. The combination of mesh and shotcrete forms a panel or plate that is typically bent by ground extruding between restraining rockbolts. The ground pressure applied (that is, the resistance of these panels to bending) over large ground deformations is important for maintaining ground support safety. This paper describes a new test device that measures this resistance and its evolution over large deformations. Mixes of shotcrete, mesh and other components that can maintain significant support pressure are desired, a characteristic described as the “toughness” of support. Results show toughness depends largely on how shotcrete is integrated with other components. Shotcrete strength is less important. INTRODUCTION Ground control safety often depends on supporting, or at least containing, the ground between the rockbolts. Shotcrete and mesh, in various combinations and with other components, are often called upon to do this (Figure 1). Applications are especially common in mines with squeezing ground or seismic loading. The support pressure maintained during ground deformation is key to the performance of these systems, and to protecting miner safety. However, the toughness of a design is difficult to estimate. Researchers at the Office of Mine Safety and Health Research (OMSHR) responded to this deficiency or “gap” by designing a full scale test device, described in this paper, and beginning a testing program. Some initial results from this program are reported to demonstrate test capabilities.BACKGROUND - TOUGHNESS Mining in ground that fails from the combination of in situ and mining induced stress is commonplace. Ground support elements are installed to reinforce such ground and preserve mine safety. Typically, the strength of support is considered key, and is used to prevent or halt yielding. However, ground movements driven by creep of weak ground or seismic loading may be impossible to halt altogether. In these cases, it is essential that support is able to yield with the ground in a safe manner while maintaining confining pressure that mobilizes the strength of rock in the immediate perimeter of the opening. In addition, it’s usually desirable to contain ground between rockbolts to protect miners from loose rock that might fall or be ejected. Shotcrete and screen are often employed, sometimes together and in combination with other support elements, to accomplish this function. A key characteristic of such a system is its ability to maintain support pressure through large ground deformations, a characteristic often called “toughness” – especially in support systems incorporating shotcrete. Toughness can be quantified as the work done during deformation (e.g. force x displacement)."

Jan 1, 2015

By John D. Elmes

The purpose of this paper is to describe the geology and the modelling work carried out to date. The Lisheen Zinc-Lead deposit was discovered in April, 1990. The deposit comprises two stratiform sulphide orebodies, hosted within the Lower Carboniferous Waulsortian limestone formation. The fully diluted geological resource is 22.5 Mt @ 13.02% Zn and 2.19% Pb, based on a total of 548 diamond drill-boles and 10,998 sampled core intersections. Due to the absence of a geological marker it was necessary to apply economic criteria to define and model the resource envelope. In common with other drill-hole geological databases, the establishment of a workable geological model presents unique challenges.

Jan 1, 1998

By William H. Engelleitner

Agglomeration by balling in cylindrical or shallow pan devices dates back to the early part of this century. The first sintering tests conducted by Dwight-Lloyd on nonferrous ores included a mixing step for ore, flux and fuel carried out in a deep pan device similar to the balling pans, or discs, presently in use. Further work directed mainly toward sintering of ferrous and nonferrous ores always included a preparatory step, usually referred to as mixing, agglomerating or green-balling of the ingredients. In the late forties and early fifties two methods of particle preparation prior to firing were in general use. In Europe the balling pan was used predominantly, both as a mixer and as a pelletizer. In the United States many pilot plants and semi¬commercial plants used balling drums. When the first iron ore pelletizing plants were built in this country, the most frequently used device for green-balling was the cylindrical drum. At the same time, the pan device was used both in Europe and the United States for many other materials such as fertilizer, cement, flyash, alumina and copper concentrates, as well as to mix the feed for sinter machines. The difference between these two balling devices - -the drum and the disc - has been the subject of much discussion and is well covered by several papers included in the 1962 publication "Agglomeration' issued by AIMS, based on their 1961 International Symposium held in Philadelphia. (1)

Jan 1, 1965

By E. P. Evert

Profitable marketing of most minerals is dependent upon the total delivered cost to the user. Transportation costs are often greater than the value of the mineral f.o.b. the mine or processing facility. In some cases, transportation costs are three to five times the mineral cost. For many years, transportation costs were controlled by a complex system involving the transportation companies and supervised by regulatory agencies. This paper will deal with the effects of deregulation on rail costs and outline the major changes in transportation economics.

Jan 1, 1985

By R. J. Smith

Tar sand deposits in Utah represent more than 25 billion barrels of in-place bitumen, 96% of the known U.S. reserves. The technological development of a hot water processing strategy for the Canadian tar sands and the commercial Production of synthetic crude oil from this natural resource suggest that similar success may be possible for the utilization of Utah tar sands to provide our country with a new domestic source of synthetic crude oil. In this regard an active research program to develop a hot water processing strategy for Utah tar sands has been sustained at the University of Utah for the past five years. The hot water process for Utah tar sands differs significantly from that used for Canadian, tar sands due to the inherent differences in the respective bitumen viscosities and the nature of the bitumen-sand association. These differences have led to the identification of certain design criteria necessary to achieve satisfactory phase disengagement during digestion. (8,9) Subsequent flotation of the digested tar sand is a subject of current attention and is considered in this contribution for the Asphalt Ridge tar sand deposit. Although contact angle measurements of pure Asphalt Ridge bitumen indicate moderate hydrophobicity, air bubble attachment to the bitumen concentrate taken from a 37 liter flotation cell is not possible. This surprising result suggests that the flotation separation is dependent on air bubble entrapment rather than on attachment due to surface hydrophobicity. The occlusion of air bubbles in the bitumen is apparent from visual examination of the concentrate, especially at lower temperatures. It seems that a bitumen bubble agglomerate forms in the impeller region of the flotation cell, the effective density of which is such to allow the agglomerate to float to the surface. A factorial design of the major operating variables in the flotation separation indicated that the quality of separation was significantly dependent on the flotation temperature and to a lesser extent on the degree of agitation. For a flotation temperature of 77C recovery of 96.7 percent was realized at a grade of 61.0 percent bitumen. The improved separation at higher flotation temperatures was found to be due to the decrease in bitumen viscosity resulting in more effective rejection of coarse sand from the concentrate.

Jan 1, 1980

By G. A. Campbell

This paper considers the international market trends of the rare earths and how they are strongly influenced by the by-product/co-product nature of their mining and processing. The two main economic minerals for the rare earths are bastnasite and monazite. Monazite is primarily a by-product of mining ilmenite and rutile and is affected by changes in these markets as well as the presence of thorium. Bastnasite is a by-product of mining iron ore in China and a stand-alone product in the USA. The paper will use conceptional relationships and empirical data to delineate the various by-products/co-products relationships and how they determine observed international market behavior.

Jan 1, 1996

By Donald Babbitt

In 1971, during the planning and design stages of a $300 million expansion, the Iron Ore Company of Canada Ltd. through its Engineers, Canadian Bechtel Ltd., came out with a preliminary request for two (2) 10,000 LTPH belt conveyor scale systems. These Systems were to provide weighing accuracies within 2.5% of the iron ore pellets and concentrates in transit on two (2) 72" wide conveyors from the stockpiles to the ships. Each conveyor system would be fed by a rail mounted bucket wheel reclaimer, with the conveyed material moving directly to the ship loaders with no inter- mediate surge and/or storage bins between the stockpiles and the ships. The bucket wheel reclaimer discharge rates would vary from 0-9600 LTPH in cyclic periods, with the periods varying from 1-5 minutes - dependent on the level of the reclaim buckets in relation to the stockpile as well as the slewing rate of the reclaimer. There would be frequent interruptions for bucket wheel repositioning (laterally and vertically), changing ship holds, and trimming ship holds. These frequent zero flow conditions, approximately 500 per 150,000 ton ship, could last 1-5 minutes. In addition, the conveyors on which the scales were to be mounted would be over the water and subject to the wind and cold of Northern Quebec. These Systems would be in use 350 working days of the year and would load 30,000,000 LT/yr. (An average of 90,000/working day).

Jan 1, 1975

By X. Yin

Surface force measurements based on atomic force microscopy (AFM) are used to describe the wettability of surfaces, specifically kaolinite basal plane surfaces at a high resolution. The kaolinite particles (~500 nm) were ordered with either the silica tetrahedral face exposed or the alumina octahedral face exposed, and surface force measurements were made between a hydrophobic diamond-like-carbon (DLC) tip and the kaolinite faces at pH 4, which is around the isoelectric point of the DLC tip. Under these conditions, the effect of electrostatic interaction should be eliminated and only van der Waals interactions and hydrophobic-hydrophobic interactions are expected to contribute to the surface force. The wettabilities of the surfaces were determined from the magnitude of the surface force. Wettabilities of the kaolinite basal planes thus determined were compared with the corresponding wettabilities of talc and mica surfaces, which are well-known to be naturally hydrophobic, and hydrophilic surfaces, respectively. The results reveal that the silica tetrahedral face of kaolinte has a modest level of hydrophobicity, which may be due to the lack of hydrogen bonding sites. In contrast, the alumina octahedral face showed no hydrophobicity, since a layer of surface hydroxyl groups is present at the alumina face, resulting in a relatively strong interaction between this surface and water molecules. It is expected that, with a better understanding of the surface properties of kaolinite, further improvements in flotation separations and dewatering may be achieved.

Feb 1, 2012

By Jennifer B. Leinart

With the signing of the North American Free Trade Agreement (NAFTA), Canada, the United States and Mexico entered into an international experiment in economics amid a cloud of controversy that still lingers. Central to the controversy are the disparities in wages that exist among workers in the signing countries. Wage surveys completed by Western Mine Engineering show the degree of disparity that exists among the mining industries of those three countries. Labor costs constitute 30% to 50% of operating costs. So these wage differences are a matter of interest to the mining industry. It is unclear how much of a factor they are in determining where companies search for and develop new mines. That depends on where minable deposits are expected to be found. However, a deposit that may not be minable in the United States or Canada may be minable in Mexico because of lower labor costs. Some adjustments are anticipated for the Mexican mining industry if and when its wages begin to approach comparability with US and Canadian wages. Table 1 combines the results of four recent surveys. It lists benchmark wages for mining job titles common to all the countries. About 220 mines are covered by the combined surveys. Canadian miners' wages, converted to US dollars, are typically 75% to 95% of US wages, while Mexican miners' wages are less than 10% of those in the United States. Table 1 also shows that wage disparities are not confined to international borders. In fact, the difference in average wages between the US coal industry and the US metal and industrial mineral industries is greater than between the Canadian and the US mining industries overall. Table 2 shows that managerial, technical and administrative salaries show similar, but less pronounced differences among the three countries. Salaried personnel at Canadian mines earn 80% to 90% as much as their US counterparts, while those in Mexico earn 20% to 30% as much. Here again, average US coal salaries exceed average salaries for the US metal and industrial mineral industries.

Jan 1, 1998

By S. S. Churchill

Introduction Amidst the apparent chaos of the final push to complete a major construction project, a small group of specialists works with great intensity. Armed with yellow "in test" and green "turned over to operations" tags, these startup engineers follow detailed preoperational test procedures to confirm that a plant is ready to operate. They follow a test schedule designed to complete individual process system in the order they will be needed by operations. After extensive preliminary testing, the startup engineers begin the truly exciting part of their work - initial operations. The thrill of engaging the clutch for the first time on a 10,000 horsepower grinding mill makes all the long hours worthwhile. Preoperational testing and startup are of critical importance to the success of a project. No other aspect of a construction project allows such opportunities for success or failure, and no other aspect is so critically influenced by careful planning. At Bechtel, the tasks of preoperational testing and startup are among the responsibilities of the Mine and Plant Operations group. The Preoperational Testing Process Preoperational testing is the transition phase between constructon and startup on a new plant. It includes the preparation of detailed test schedules and procedures. The schedules are used to coordinate construction completion activities, so that systems are available for startup and operations in a rational sequence. The procedures form the basis for performing the testing and documenting its completion. Tests include instrument calibration, wire insulation tests, wire termination verification, mechanical alignments and inspections, and system cleaning and flushing. Where possible, the systems are then operated on water and their performance recorded. Normally, either the construction contractor or a team of specialists has the responsibility to perform preoperational testing. Witnesses to the testing may be owner operations and maintenance personnel, engineers from the design firm, or specialists assigned to the project who provide assistance and guidance to the contractor in addition to witnesing the work.

Jan 1, 1986

By R. J. Heath

Potassium, together with nitrogen and phosphorous, is one of the essential nutrients required for growth. All living things need potash and so the major demand for potash (approximately 95% of, total demand) is as a fertilizer. Traditional agricultural techniques relied on the return of organic materials to the soil to provide nutrient requirements and maintain soil fertility, and the prevailing low crop yields required little in the way of added fertilizers. But agricultural productivity has increased dramatically in recent times, and this increase in crop yields requires substantial amounts of added nutrients to keep the soil fertile. It follows that there will always be a demand for potash. There is no substitute. Other fertilizers that contain N and P are complementary and not competing products.

Jan 1, 1987

By Tegner C. Johnson

Just a few years ago my company was referred to as the Marion Steam Shovel Company. We still make shovels, both two and eight crawler types. The eight crawler stripping shovel appears to have been replaced by the walking dragline for overburden removal and in some cases for the mineral as well. The walking dragline appeared in the coal fields in the early 1930's. It owes its popularity today to the fact that it can cope with overburden depths in excess of 100 feet and with blasted sedimentary rock, all at an 0 & 0 cost of ± 10¢/BCY.

Jan 1, 1974

By W. J. Roberds

A formal and explicit yet cost-effective approach is proposed to ensure that decisions made during mine development are optimum (with respect to their ultimate consequences) as well as defensible. This risk management approach is based on probabilistic risk assessment and established decision analysis techniques, and appropriately considers the relationships among various mine development decisions, tradeoffs among consequences, the uncertainty in predicting consequences, and the benefits of flexibility to respond to changed conditions.

Jan 1, 1992

By G. Chancellor

"INTRODUCTION The paste plant is located at the Barrick Goldstrike mine in Northern Nevada on the Carlin Trend. The Goldstrike property consists of an open pit and an underground mine; along with two processing facilities: a roaster and an autoclave. The underground portion of the mine produces approximately 1,800,000 ore tons per year and approximately 400,000 ounces. The mine is broken up into four distinct zones: Banshee, Meikle, Rodeo and Northpost. The current paste plant services both the Rodeo and Northpost zones. Development of the conceptual designs and permit approval for this plant was an extensive process that took over a decade to complete. A testing program was developed in conjunction with this process and implemented throughout to ensure the following metrics were achieved: ensure no environmental impact, material available onsite would be able to flow through the pipe to all required locations, and that this material could achieve the appropriate final strength. PLANT AND UNDERGROUND CONSTRUCTION This is the first paste plant to be built in Nevada. The paste plant at Goldstrike began construction in January 2012 and was completed in March of 2013. This plant was constructed to service the Rodeo side of the underground mine which previously utilized a cemented rock fill (CFR) plant to meet their backfill needs. However, in March of 2013, the same month the plant was commissioned, the raise that fed this CRF plant was mined out in a planned phase of the adjacent open pit. This made the switch to paste all the more difficult as it was being relied on for as the sole source of backfill production even though the system yet to be fully tested and optimized. The plant was designed to be fed with onsite Roaster tailing which would be thickened and then mixed with cement and fly ash. The plant was designed to pump 177 tons of paste per hour with a utilization of 65%. The original design specifications for the paste were 77% solids with varying binder contents depending on where the paste was being placed"

Jan 1, 2015

By Fatima-Zahra Houmymid, Elena Chiriotti, Mahdi, Samy

"The Greater Paris projects involves the creation of a 200km extension of the actual public transport network on the close outskirt of Paris. In 2011, SYSTRA has been awarded the Engineering studies of a 20km underground section in the densely urbanized southeast quarter of the Parisian suburb. In order to both guide the TBM technology choice and identify and mitigate the risk due to soil settlement during tunnel boring, several analysis have been carried out and integrated into a Geographical Information System to share and manage this risk during the successive design phases of the project. The geological context‘s complexity and the Owner‘ requirements have led to the necessity of using an innovative analysis approach, leveraging both the numerical modelling analysis’s accuracy and the analytical method‘s ease of programming and implementation in a GIS, by the mean of the calibration of the analytical approach’ parameters on the FEM results.INTRODUCTIONThe Greater Paris Transport Project foresees the extension of the actual public transport network to the close outskirt of Paris through the extension lines 11 and 14, the creation of a circular new line around Paris - line 15 completed by lines 16 and 18 linking developing territories - and line 17 to Roissy-Charlesde- Gaulle airport.The SOCIETE DU GRAND PARIS (SGP) is the public institution that promotes this project and awards SYSTRA as Engineering for the 15th Line southeast section.Line 15th – South-East sectionIn 2011, the Owner SGP (SOCIÉTÉ DU GRAND PARIS) awarded to SYSTRA the preliminary and detailed design of a 20km-long underground section of Line 15, between the stations of Villejuif-Louis-Aragon and Noisy-Champs. The double-track, single-tube tunnel has an inner diameter of 8.5m (about 9.8m excavated diameter, 75m2 excavated cross-section). The tunnel is inserted in a densely urbanized context."

Jan 1, 2016