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By Raúl Castro, Marco Vera, Alfonso Ovalle

The underground mining evolution for block cave mines in Chile and worldwide has made important strides in the last decades. Nonetheless, reserves determination in the initial stages of these types of projects—mainly for long-term planning—is not studied in as much detail as it should be, especially regarding the impact on the final value of the enterprise. Today, the first estimation of the size of a block cave mine, typically expressed in tons, tends to determine very large footprints and ore bodies. The resulting large-scale mine is obtained by applying the marginal cut-off grade (COG) to determine reserves. Yet, in many cases, it is possible to obtain an equal or higher benefit, extracting fewer reserves in less time, with a smaller active area, which significantly reduces the project’s uncertainty. To explore scenarios obtained by applying a higher marginal COG in the initial phases of the project, the Hill of Value methodology is used to estimate the net present value (NPV) in relation to the production rate and the COG. However, the application of this methodology considers certain simplifications that generate results which are not completely satisfactory in specific cases. This paper suggests an improvement of this method to obtain more reliable results regarding determination of a COG profile that will optimize the NPVof a block-cave project. The methodology was developed and applied in a massive polymetallic deposit with zinc, lead, and silver mineralization, corresponding to a real block caving project. The methodology provides NPV results that differ by approximately 15% in comparison to the real mine plan, while also being considerably simpler and faster to calculate. In summary, the proposed methodology provides a reasonable and fast procedure to estimate higher than marginal COG that increases the NPV of block cave mine projects.

By ERIK CHARRIER, ADITYA JUGANDA, Jürgen Brune, Gregory Bogin, Patrick Maier

Confined explosions are a major risk in underground coal mine operations. Depending on confinement, ignition location and obstacles in the flame path, methane explosions can transition to detonations. This research focuses on explosion experiments in a reactor with diameter of 71 cm and length of 30.5 m, along with developing the corresponding computational fluid dynamics (CFD) model that captures the observed flame behavior. The results show that the 2D and 3D CFD models are able predict the experimental flame front propagation velocity, but the 3D model shows more explicit conformity than the 2D model.

May 1, 2024

By Vladimir Nikolić, Alex Doll

The Bond ball mill grindability test is one of the most common metrics used in the mining industry for ore hardness measurements. The test is an important part of the Bond work index methodology for designing and measuring the efficiency of mineral grinding circuits. In spite of being called “Bond’s Law,” the work index equations are not a law of nature; but rather an empirically measured regression of a large data set collected by the Allis- Chalmers corporation in the period between 1930 and 1952. As a regression, it is valid within a specific “calibration space,” and great care is required when deviating the test procedures or observing results that are outside of that calibration space. This paper is a collected summary of other works by the Authors that describe feed sizes, product sizes, quality control checks, and other information about interpreting the test and using its results. Examples of adjustments that are sometimes required when using the test are: changing the test product (P80), and coping with a feed that is too fine to apply the “proper” feed preparation steps (such as is sometimes observed from HPGR or SAGDesign product testing). Related metrics, like the Morrell Mib value and Levin B value will be discussed, along with recommendations for their use on design projects. The intended audience is any user of laboratory work index test data.

Feb 1, 2024

At the 25th Peruvian Mining Convention, the start-up of Antamina was called ?the mining event of the year.? Antamina, one of the largestcopper-zinc mines in the world, began operations in May 2001.Augusto Baertl is Executive Chairman of Compañía Minera Antamina, the operating company. He said in a convention address that Antamina would be in full production in 2002. ?I would like to stress that Antamina is, in every respect, a highly stringent operation, as it intends to be the Peruvianmine of the future,? Baertl said. ?Antamina has set the target of being, and remaining throughout time, a model mine as to technology, environmental practices and social responsibility.? [ ] In the areas of technology and operations, Baertl noted that ?we have incorporated the best engineering design available and state-of-the art technology for mining, grinding and transportation processes, among others.? In the environmental area, he said that ?we have carried out careful environ-mental impact studies and have incorporated modern technologies and methods to control and minimize any environmental impact.? In the social field, Baertl noted that ?our relationship with neighboring communities is being developed under the premises of the social responsibility philosophy.? These include popular consultation processes, environmental committees and conciliation discussion committees. The purpose, he said, is to encourage communities located within the area of influence of the project to find and lead by themselves their path toward sustainable development, beyond the life of the operation itself.?

Jan 1, 2001

By H. Kempton

New methods for remediating metals-contaminated groundwater include in-situ emplacement of highly adsorptive substrates to permanently retard solutes. Substrates are introduced by sequential injection of soluble components that precipitate in the aquifer, forming a permanent high-retardation zone. This method overcomes the factors that limit pump-and-treat remediation; i.e, long-term source loading and slow desorption. Column tests demonstrated efficient substrate emplacement, increasing retardation coefficients of Cr(VI) by 20 and As(V) by 40. Similar effectiveness is expected for other heavy metals. Simulations using a coupled advective-geochemical model accurately matched substrate emplacement and arsenic attenuation, allowing extrapolation to other constituents and larger-scale applications.

Jan 1, 1999

By Liming Yuan, Wei Tang, RICHARD THOMAS, DAVOOD BAHRAMI

The location and orientation of fire suppression nozzles is critical in suppressing mobile mine equipment fires. To effectively suppress such fires, optimization needs to be considered for the suppression nozzle locations and discharge angle. Detailed experiments were conducted to study the effectiveness of fire suppression agents with different nozzle configurations. A variety of fire suppression systems including dry chemical, wet chemical, dual agent (dry and wet chemical), carbon dioxide, and water mist were used. Six types of nozzle locations were studied, and their fire suppression effectiveness were compared. Results from this work highlight potential considerations when determining effective fire suppression designs.

Feb 1, 2025

By D. R. Nagaraj

The chemistry and structure-activity relationships for four new classes of sulfide mineral and precious metals collectors developed recently are discussed in this paper. These collector classes are alkoxycarbonyl alkyl thionocarbamates and thioureas, dialkyl (or diaryl) monothiophosphates and dialkyl monothiophosphinates. The main emphasis will be to highlight the differences between collectors and their affinities for various minerals on the basis of data on kinetics of adsorption on pure minerals, natural ore flotation and microscopy of flotation concentrates. The mechanism of interaction of these collectors with sulfide minerals is also discussed with the available data on the FTIR and solution chemistry studies.

Jan 1, 1989

By H. H. Murray

New and improved benefication techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques including particle size separation, high intensity magnetic separation, chemical leaching, flotation, and selective flocculation are described and results and applications are discussed. The blending of clay minerals with other minerals provide opportunites to make special ceramic materials such as cordierite and other minerals which have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1989

By M. R. Rosen

CARBINDER Polymer 498 is a liquid organic taconite binder which significantly improves fired compression in both fluxed and acid pellets. It has been used commercially in both shaft and straight grate furnaces. This new binder produces an unusual wicking phenomenon during balling wherein the rate of movement of interstitial water is accelerated to the surface of the balls. The phenomenon is proposed to be responsible for the significant improvement seen in fired compression. This paper presents information as to the effect of CARBINDER Polymer 498 on green ball and fired pellet properties. It also describes the wicking phenomenon and discusses a reversal in the normal balling operation procedures required for successful agglomeration.

Jan 1, 1988

By Yi-Hsuan Chen, Jürgen Brune, Candace S. J. Tsai, Alejandro Munoz, Connor Krause

This study highlights the significant presence of submicrometer- sized airborne particles in underground coal mines, especially around the belt conveyor drift areas. Using realtime instruments and gravimetric samplers, the assessment revealed that particle concentrations were notably higher in the belt entry compared to other locations, with a strong presence of submicrometer- and nanoparticle-sized dust. The study’s findings emphasize the importance of addressing small particle exposure, as these particles, composed of harmful substances like calcium, copper and iron, can pose serious health risks to miners. This research emphasizes the importance of improving air exposure estimation through more effective monitoring and characterization techniques to better understand and reduce workers’ exposure to hazardous airborne particles in the mining environments.

Apr 1, 2025

By Ruifeng Li, Yanghui Ren, Hua Gao

"Since entering the new century, China’s coal industry has witnessed the rapid development, and provided a reliable energy supply for the national economic and social development. But after the “golden decade” of rapid development, the coal industry now is facing overcapacity, low industrial concentration and production efficiency, high pressure of production safety and environmental protection and other prominent issues. Based on defining the connotation of highly-efficient recovery of coal resources, this paper established the relevant 8 indicators to reflect the highly-efficient recovery level of coal resources, summarized the present situation of China's coal resources recovery and the main problems, analyzed the development environment of China's coal industry under the new situation, and finally put forward the strategic measures to promote highly-efficient recovery of coal resources in China.1. Background Coal is the main energy in China. Since entering the new century, China's coal industry has made significant progress, and the level of production safety, resource recovery rate and mining mechanization increased significantly, which provided a reliable energy supply for the rapid development of the national economy. However, due to the changes of China's economic environment, slow growth of energy demand and other factors, some prominent contradictions in the coal industry have significantly restricted the healthy development of the industry. The first problem is serious overcapacity. In the past few years, 16 industries including coal, electric power, chemical and others have invested in coal mines. It is reported (Han 2016) that only during the nine years from 2005 to 2014, the fixed assets of coal industry increased totally more than 3.3 trillion RMB, which brought a large number of production capacity. Affected by the slowdown of economic growth and energy structure adjustment, Chinese coal demand has reached the peak platform and caused the overcapacity of coal supply, so shutting down the backward capacity is the most important task in the future. The second problem is the low efficiency of coal production. There are about 4.3 million coal mine workers in China, and the annual coal production per capita is less than 900 tons, while it was reported (EIA 2016) that the annual production per capita in the United States is more than 10 thousand tons. The third problem is that the green coal resources are not rich. Among the 1.53 trillion tons proven reserves, only about one third are green coal resources in accordance with the principle of ""safety, technology, environment and economy"". The coal resources with high quality and easily mining conditions are not abundant."

Jan 1, 2017

By John K. Liu

The trend to larger grinding mills, requiring total drive power in the range of 10,000 KW(13,400 HP) or so provides the incentive for developing new power transmitting techniques, since conventional girth gears are limited to about 3700 to 4500 KW per mesh (5000-6000 HP). For the immediate future, the synchronous motor, with its beneficial power factor, and the squirrel cage induction motor, with its high reliability record and low maintenance, still promise to be the best choice for prime mover(s). Due to the abovementioned single mesh power limitation of the gear train, however, two or more motors must be combined to attain the required drive power. This paper describes a scheme for coupling these motors to the mill using a straightforward, essentially mechanical means that is based on proven components and controls.

Jan 1, 1977

By E. Wiewiorowski

A new technology for recovery of metals from spent catalysts containing aluminum, cobalt, molybdenum, nickel and vanadium was developed. The catalysts are decomposed in two consecutive pressure leaching steps. Sodium aluminate-sodium hydroxide systems are lixiviants in both leaching steps. Selective extraction of molybdenum and vanadium is achieved in the first leaching step. The leach liquor is processed for separation and recovery of these two metals. The residue from the first leaching step is further processed in a second leaching step where alumina is solubilized. The residue from this operation is a nickel-cobalt concentrate. Alumina is separated from the second stage leach liquor by precipitation; the depleted liquor, a sodium aluminate solution, is recycled to the first and second leaching step. This technology has advantages over other approaches for the recovery of metals from spent catalysts because no solid waste is generated.

Jan 1, 1988

By Harry C. Oussoren, James C. Miles

A new seven kilometer long subway line is being constructed through dense glacial soils under a major thoroughfare in Toronto. Eductor, deep well and vacuum wellpoint systems are being used to lower the water levels by as much as 16 metres for the construction of the twin tunnels and associated structures. The design and performance of the dewatering systems will be described. Unanticipated difficulties and their solution will be presented.

Jan 1, 1999

By B. Ni, J. D. Robertson

A new radioactive tracer method for the measurement of airflow in inaccessible airways was developed. The method can be used in situations where studies of the mine-ventilation system are not possible using conventional flowmeters (anemometers). The method was tested in the ventilation laboratory at the University of Kentucky and in the US Bureau of Mines Experimental Underground Coal Mine and was utilized in leakage, dilution and flow-velocity measurements.

Jan 1, 1998

By Kenneth W. Torpey, James G. Ball, Richard F. Flanagan, David S. McAllister

INTRODUCTION Under a Federal grant by the Urban Mass Transit Administration (UMTA) (80%), and sponsored by the State of New York (200), Niagara Frontier Transportation Authority is constructing a 10.3 km (6.4 mile) light rail rapid transit system in Buffalo, New York. The $450 million project, which began construction in the Spring of 1979, is unique in rail transit alignment designs in the U.S.A. and the first predominantly underground light rail system in North America. The Buffalo project is unique in that the first phase of the expandable system follows the alignment of Main Street and is on the surface in a proposed 1.6 km (1.0 mile) pedestrian mall in the downtown business district. The alignment then progresses northward into a cut-and-cover portal and standard double-box configuration for 2.74 km (1.7 miles) at a depth of 9.1-10.7 m (30-35 ft) and subsequently drops into bedrock at depths of 18.3-27.4 m (60 to 90 ft). The 5.63 km (3.5 mile) rock tunnel section consists of two single tunnels 4.88 m (16.0 ft) nominal finished diam. and includes five stations. The rock tunnel line section was divided into a north and south contract of 2 316 m (7,600 ft) and 3 243 m (10,640 ft), respectively. Due to the existing surface facilities and the future station locations, the line tunnel contracts differed considerably in their shaft access

Jan 1, 1981

By A. J. Nugent

Investigations were undertaken to evaluate peroxygen compounds for effective­ness in alkaline cyanide leaching of gold. The addition of peroxygens improved the leach results. Calcium peroxide was the best performed reagent to be employed. Improved reagent consumption followed the trend of calcium peroxide> hydrogen peroxide> no peroxygen addition. In general, preaeration stages could be eliminated, and improved leach rates achieved with no detrimental impact on leach perfor­mance. Interox has not developed an Au Plus (Trade Mark pending) system to utilise this new leach reagent. Initial plant trials are verifying its potential to give additional benefits.

Jan 1, 1990

By A. Kaczmarek

As the mining industry is enjoying a much needed and long awaited increase in demand for natural resources, consolidations in both the mining and mining service industries and a generational departure of experienced industry professionals is challenging today’s mining companies, not only in maintaining their existing operations, but also in securing qualified resources for developing new projects. These challenges are compounded for junior mining companies, oftentimes lacking in operating properties to draw from for experienced professionals and having to compete with the majors’ “mega-projects” for experienced project personnel from the reduced ranks of engineering companies. This paper discusses some strategies developed by Anatolia Minerals Development Limited in developing its Çöpler Gold Project in central Turkey.

Jan 1, 2006

By K. K. Cheng, Z. M. Chen, A. L. Mular

INTRODUCTION Since the nineteen fifties, process engineers have been seriously concerned with process models for various purposes (1,2,3). Models serve as subroutines to mathematical flowsheets which simulate circuits of interest. Simulators can serve to increase process know- ledge, assess circuit performance, investigate flowsheet modifications, evaluate new flowsheets, perform off-line optimization, and compare alternative control strategies. This chapter describes a methodology to develop a simulator of a bulk Cu-Mo circuit comprised of roughers, scavengers and 3 stages of cleaning. The simulator was employed to evaluate the influence of water addition at circuit points and to estimate the optimal number of cells for each stage in the circuit. DESCRIPTION OF CIRCUIT Figure 1 is a flowsheet of the Brenda Mines Ltd. (located near Peachland, B. C.) bulk Cu-Mo flotation circuit as simulated prior to an expansion/renovation which involved the installation of large, new flotation cells. Referring to the flowsheet, feed to rougher cells includes fresh feed, scavenger concentrate and 1st cleaner tailing. Rougher con, 1st cleaner (sect ion 2) con and 2nd cleaner tailing are fed to 1st cleaners (section 1). 1st cleaner (section 1) concentrate and 3rd cleaner tailing serve as 2nd cleaner feed, while 2nd cleaner concentrate is fed to the 3rd cleaners which produce a final bulk concentrate. Table 1 lists cell types and specifications important to the circuit. DEVELOPMENT OF MODELS To develop flotation cell models a systematic procedure was employed (4). This involves the selection of responses and factors, proposing models to be fitted, the acquisition of raw data, the statistical adjustment of raw data, fitting models to adjusted data and testing the adequacy of fitted functions. Responses and Factors Responses of interest included recoveries, concentrate grades and concentrate solids/water flow rates for each stage. Factors that influence these responses, such as reagent addition rates, air flow rates to cells, solids and water flow rates to stages and feed grades were not manipulated during the sampling period. Thus, the investigation was limited,

Jan 1, 1986

By James W. Collins

The bucketwheel stacker/reclaimer is suited for a variety of bulk material handling systems, especially those operating with stockpiles in excess of 30,000 tons. The bucketwheel stacker/reclaimer, although relatively new in the United States (first introduced here in 1964), has been successfully used in European countries since the early 1940's. Basically the machine is the outgrowth of the bucketwheel earth excavator and the traveling tripper boom type stacker. Since their introduction here they have achieved wide acceptance, especially with coal fired power plants. (Figures 1, 2, and 3.) The stacker reclaimer has been utilized in barge and ship loading/unloading facilities, and in the material handling systems for steel mills, where it has been used to stack and reclaim iron ore at rates up to 6000 tph stacking and 4000 tph reclaiming. They have also been employed at mine mouth power plants for the handling and storing of the plant fuel supply and to help balance the mining rate with the fuel consumption rate.

Jan 1, 1973