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By D. P. Patil, B. K. Parekh

Water is the mainstay for beneficiation of fine size coal and minerals; however, it is also the least desirable constituent in the final product. The basic concept of the novel process described in this paper is based on the differential surface heat absorption capacity of individual particles, which differs for different species of mineral. When a mixture of fine material is exposed to a radiant energy source, the various solids components present in the mixture will absorb heat energy depending on their composition and there will be difference in the surface temperature of the particles. When this differentially heated solid mixture is placed on a moving belt, which is coated with low temperature melting resin, the hotter component of the mixture will stick to the belt and relatively cooler will stay free on the belt and fall off at the end of the belt run. Experiments were conducted with pyrite, coal and quartz of 6 x18 mesh particle size. The goal of the test program was to find the optimum conditions at which there exists a required temperature difference between minerals and coal particles by controlling the operating and system variables. Preliminary tests results showed that there is a potential for separating mineral matter from coal using the thermo-adhesive separation technique.

Mar 2, 2022

By F. J. Sotillo

Mineral processing requires good classification of particles to attain an adequate separation of minerals. This is of utmost importance in the case of sulfide minerals. An ideal classification is obtained when particles are separated at a given mesh, which is fixed according to the characteristics of each sulfide ore. Under these ideal conditions, particles coarser than the mesh of separation are recovered in the underflow, whereas particles finer than the mesh of separation are recovered in the overflow. This paper presents the results of pilot plant tests that were performed on Ag-Pb-Zn and on Ag-Au Peruvian sulfide ores using a Density Separator, and the comparison of these results with those obtained using hydrocyclones, under similar operating conditions. The results show that the ratio of circulating load is reduced by 50% by using a Density Separator with respect to that obtained by using hydrocyclones. Moreover, the effect of the improvement in the separation efficiency obtained by using the Density Separator on the kinetics of flotation is also shown. Silver recovery of the Ag-Pb-Zn ore increased by 18% whereas gold grade in the concentrate of the Ag-Au ore is doubled.

Jan 1, 1998

By J. H. Gasper

The overall success of steep slope (>20°) contour mining is dependent upon many factors. The major factor is the selection of the mining method that best suits the premining site conditions both environmentally and economically. These conditions can be divided into three major categories: 1) Geometric Conditions --machine limitations, slope stability restrictions, erosion capacity, among others; 2) Physical Conditions--material properties, rock strengths, diggability, driving surfaces, among others; 3) Chemical Conditions --acid/base relationships, blending or selective placement of overburden, among others. This paper incorporates these conditions through conceptually modeling compliance oriented contour mining methods; in particular Haulback methods, utilizing: 1) the Front-End Loader (FEL)/Truck; 2) Tractor Scrapers; and 3) Combined FEL-Truck/Scraper. Engineering analyses including machine selection, sequencing, ease of varying production rates, slope requirements (for stability and running surfaces), drainage requirements and many others can be performed after the geometric constraints dictated by in-situ conditions and regulatory requirements have been conceptualized. Once all generalized geometries have been established, reduction to idealized three-dimensional views is achieved. These are then reduced to two-dimensional symbolic models, mainly plan views, but also elevations and sections. Equipment activities and operations are then conveniently overlayed. Without this simple two-dimensional reduction, technology transfer remains awkward and non-analytical.

Jan 1, 1991

By Dan Nilsson

INTRODUCTION There are many mine planning factors in sublevel caving, as in the other mining systems, which when varied can substantially alter mining costs and profit¬ability. In this chapter, the following four topics are addressed with regard to economic optimization of sub¬level caving: production planning, haulage level spacing, orepass spacing, and extraction cutoff. The costs used here are the right order of magnitude but since each mine is unique, they should be considered only as examples. The objective is to demonstrate the tech¬niques which can be used. In a real mine, the evalua¬tions must be done using actual costs and conditions. It is difficult to predict exactly the costs involved, and therefore it is valuable to perform a sensitivity analysis to evaluate the effect of making incorrect as¬sumptions. Since the mining industry is very capital intensive, the effect of the interest rate must also be studied. PRODUCTION PLAN FOR AN IRON ORE DEPOSIT Introduction The first and most important thing to do before de¬signing an underground mine is to establish a long-range production plan. Such a plan is necessary for all eco¬nomic evaluations and should provide information about the lifetime of the mine, how much ore and waste must be handled per year, how much development per year is required, etc. An example is given in the following section. Problem In an iron ore mine sublevel caving is used. The iron content is 42%, and the mine supplies a pelletizing plant with an annual capacity of 3 million t/a. The ore body is shown in Fig. 1. The length of the ore body is 1000 m and the width is 100 m. Each slice is 10 m high, and there are 10 m be¬tween crosscuts, each of which has an area of 20 m2. The density of the ore is 3.5 t/m3. The spacing between rings is 2 m, and the extraction is 100%. The iron con¬tent is 66% in the pellets and 6% in the tailings. The problem is to develop a detailed production plan. A typical sublevel caving sequence is shown in Fig. 2. Solution Amount of ore per meter of crosscut: 20 X 3.5 = 70 t. Number of crosscuts per slice= 100. Length of crosscuts per slice: 100 X 100 = 10 000. Ore from crosscuts per slice = 10 000 m X 20 m2 X 3.5 = 700 000 t. Number of sublevel caving rounds per slice: 10 000/2 = 5000. Area for each blast in sublevel caving: 10 X 10 - 20 = 80 m2. Amount of ore per blast: 80 m2 X 6 m X 3.5 = 560 t. Extraction: 100% (see extraction curve Fig. 12). Loaded ore per blast: 75% or 420 t. Loaded waste per blast: 25% or 140 t. Total: 560 t. Total amount of rock from each blast in the sublevel caving: Ore: 560 t of which 2 X 70 = 140 t from develop¬ment work and 420 t from sublevel caving. Waste: 140 t. Total: 700 t. The ore needed per year is 3 X (66-6)/42-6 5 mil¬lion t. Necessary number of blasts per year= 5,000,000/ 560 = 8929. Distance to develop per year = 8929 blasts per year X 2 m per blast 17 858 m. Total amount/year: Ore from development work 17 858 m x 70 t/m = 1.25 million t/a Ore from sublevel caving: 8929 blasts per year X 420 tons per blast = 3.75 million t/a 5.00 million t/a Waste rock dilution: 8929 blasts per year X 140 tons per blast 1.25 million t/a Total amount to hoist 6.25 million t/ a The amount of ore from development work will in¬crease a little if the horizontal drift is placed in the ore body and not in the footwall. In this example the ore loss in 20%, and the waste rock dilution is also 20%. After taking the ore loss into account, the lifetime for 100 m of the ore body will be:

Jan 1, 1982

By Leonard Sugin

The requirements of today's and tomorrow's markets led to a new generation of facilities which handles large tonnages annually, loading them into larger vessels, at higher rates, efficiently and reliably, with minimum labor input, and significantly greater attention to the environment. A great variety of products are handled, including various grades of metallurgical and steaming coal, coke, iron ore in its many forms, shapes and moisture content, phosphates and fertilizer products, bauxite and alumina ores, limestone, sugar and grains, cement and many other products. When we examine the annual tonnages involved in these movements the economic value of handling these products on a bulk basis can be readily seen. Although nearly all these products have been handled by continuous bulk conveyors for many years, recent governmental response to environmental concerns require a re-evaluation of previous procedures. Most air pollution and emission control regulations and ordinances have recognized several specific sources of pollution. Detailed regulations and requirements have been developed concerning smoke emissions, emissions of visible air contaminants and particulate matter from power plants, heating plants, refuse burning equipment, coke ovens, steel furnaces, kilns, and other industrial installations. Although fugitive dust is also an environmental pollutant it is governed by regulations that are more general and therefore, more difficult to apply. A general definition of a "fugitive particle" is any matter which escapes or becomes airborne from an operation or which is emitted into the atmosphere without passing or being conducted through a flue, pipe, stack or other structure designed for the purpose of emitting air pollutants into the atmosphere. This paper deals with the aspects of fugitive dust emissions as they apply to shiploading. Fugitive dust emissions control is important not only because of environmental regulations but also to prevent the loss of valuable product, reduce housekeeping, and reduce breakdown and maintenance problems to land and vessel equipment. The environmental controls for a belt conveyor system are those which will restrict the emission of fugitive dust particles and can be considered as follows:

Jan 1, 1977

Conventional logging tools such as density, neutron, and acoustic have ranges of investigation of tens of centimeters. The borehole gravimeter, however, has a range up to hundreds of meters. For example, from the center of a cylindrical orebody 0.22 g/cm3 denser than its surroundings, one can detect the boundary of the orebody at a radius as large as five times its height. More complex structures can be investigated with computer programs. We can predict the usefulness of proposed gravity surveys, or decide which suggested structure is most likely to have caused the results of existing surveys.

Jan 1, 1985

By Mustafa Fener, Masoud Rostami, Sair Kahraman, Behnaz Dibavar

The paper introduces a new rock mass cuttability classification (RMCC) system for roadheaders used in coal mines. It includes performance prediction models for both axial and transverse roadheaders, based on six parameters: uniaxial compressive strength, Cerchar abrasivity index, volumetric joint count, strike and dip of joints, joint aperture, and groundwater condition. The study validates the RMCC system through field and laboratory measurements, showing high correlation coefficients between net cutting rates and RMCC indices.

Nov 1, 2023

By Gill Montgomery

The problems of the domestic merchant fluorspar producers are more or less common with those of many other producers of metallic and non-metallic minerals. For more than ten years the American fluorspar producers have seen an ever lowering price in the market-place for the fluorspar product, while their labor and material costs-continue to mount steadily. This cost-price squeeze has forced out of business all but a few of the merchant producers, and only two captive producers continue to operate, and one of them has announced early curtailment. The prices of domestic fluorspar, of all grades, have declined because of the competition from cheaper foreign imports, principally from Mexico, Spain and Italy. Tariff protection on fluorspar, particularly on the highest or acid grade, has never been sufficient to cover the production cost differential between foreign and domestic fluorspars. Low ocean and barge freight rates have also contributed to the barring of the product of domestic mines from, the major consuming centers along the Gulf and East Coast. Because of the freight disadvantage, all but one or two fluorspar producers in the western states have had to suspend business. More than 80% of the domestic fluorspar is being produced in Illinois and Kentucky fluorspar districts which adjoin on both sides of the Ohio River.

Jan 1, 1964

By Chi-shing Wang

The U.S. Bureau of Mines has been developing the mechanical roof pulling technique as a method for evaluating the effectiveness and the comparative advantages and disadvantages of various roof bolting systems, based on the characteristic responses of bolted nine roofs to a prescribed external loading system. Preliminary experiments were conducted in the Bureau's Safety Research Coal Mine using a 12-foot and a 16-foot-span test rig. The experiments have proved the capability of the test rigs and suggested the viability of the test method. This paper summarizes the test concept and the experimental results.

Jan 1, 1974

By C. Sun

Due to unfavorable geological condition, excessive deformation of mine drifts occurred in a large underground copper and nickel mine. In searching for a solution, a comprehensive underground monitoring program was implemented and the opening convergence and the surrounding rock deformation were monitored. A large number of field data were collected and thoroughly analyzed. The convergence and deformation as function of time and depth were determined and a rock stability index was proposed. Based on the deformation-time and deformation-depth relations, critical deformation times and locations were identified and defined as characteristic values to be used for mine opening and support designs. The characteristic values are critical in the application of two-step supporting system, and the determination of support parameters. The application of the method developed in this study has demonstrated that this practical approach in support design and installation is effective. With the two-step supporting system, a long-term drift stability can be achieved in the mine.

Jan 1, 1998

By Sean Warren, JOSEF BOURGEOIS

The potential of rockfall at open-pit mines presents a continuous hazard to mine workers and is typically mitigated by designing catch benches at empirically determined widths. The National Institute for Occupational Safety and Health (NIOSH) is working in conjunction with industry and academia to revisit and update current catch bench guidelines to better match acceptable risk tolerances for modern mining practices. To begin this process, a rockfall testing program was designed to gather empirical runout and bench catchment data at partnering mine sites in the Western United States. This paper presents a detailed description of each component of the rockfall testing program, including scouting and safety plan development, equipment requirements, synthetic rock development for uniform testing across varying bench configurations, local rock collection for testing of mine-specific geology, data acquisition during testing, and data processing. Additionally, this paper describes how the program has been updated over time according to lessons learned during initial rockfall testing.

Feb 1, 2024

By C. Leal

Modern production has as goal to reach high and uniform quality in their products. To success with this, it is essential to have a good knowledge of the different variables involved in the process. Investigation or analysis of a process or system has as references the measurements of the variables. These measurements are presented normally in form of data. These data are measured in intervals over time. The aim with measurement of the data in a process is to obtain information about the state of it in order to have it under control. Other goal is to know how the results are affected by the process variables to improve upon product quality, redunding manufacturing cost, better pollution control etc.

Jan 1, 1994

By Eti Purwaningsih, Widi Astuti, Erik Prasetyo

Increasing demand for high-grade manganese (Mn) ore has led to the practice of selective mining, which produced low-grade Mn ore as waste and in the long term could lead to environmental pollution. Research had been carried out to extract Mn from low-grade ore, which mostly exists as black Mn(IV) oxide (MnO2). Most extraction methods involved the reduction of insoluble MnO2 to soluble Mn2+ in acidic media. Metals other than Mn are also transferred to the pregnant leach solution (PLS) during the leaching process, especially iron (Fe). Due to high Mn concentration in PLS, precipitation is considered the best method to isolate Mn from PLS compared with solvent extraction and ion exchange/absorption. However, due to unselective leaching, the presence of Fe in the PLS makes the Mn separation and purification difficult. Therefore, in this research, the parameters affecting the selectivity of Mn over Fe in leaching process were investigated.

By E Marambio, R Brändle, G Fischer, G von Rickenbach, M Fuentealba, L Burgos, R Luis Fonseca

In underground excavations, under high stress conditions, ground support systems must provide safe and effective response to dynamic events. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the back analysis through numerical methods (central difference and Newmark’s method) of a ground support system tested with a double dynamic impact in 2019 is presented.

Apr 26, 2022

By Carl Hansen

Sonora Mining Corporation (SMC) operates the 6,000 tonne per day Jamestown open pit gold mine in the Mother Lode district of California. The mine has been in operation since January, 1987, and has produced approximately 7,800 kilograms of gold since start-up. The property consists of five ore bodies lying along a five kilometer stretch of the famous Mother Lode vein system. At present, only the Harvard ore body is being mined. The Harvard pit is centered around a historic underground mine of the same name that was operated from 1896 to 1916. The present ore body averages 2.5 grams gold per tonne as free milling gold and auriferous pyrite. The project consists of the open pit mine and concentrator complex in Tuolumne County, California, and a carbon-in-pulp leach plant located near Yerington, Nevada.

Jan 1, 1990

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

This study aims to investigate the reduction thermodynamics of ilmenite and pre-oxidized ilmenite, and reveals the isothermal reduction kinetics of pre-oxidized ilmenite concentrate by carbon monoxide. The results indicate that the ilmenite concentrate and pre-oxidized ilmenite concentrate can be selectively reduced by controlling the temperature. The pre-oxidation process leads to the breakage of complex mineral structure, and the formation of porous simple oxides, which is an effective method to increase the reduction and leaching rate. 

By C. Anderson, D. Kolstad, M. Unger

Operators are often challenged with the management of water throughout the life cycle of a mine. High water levels can lead to physical or chemical instability of water-retaining structures. Operators need to predict changes in water levels to make timely operational decisions and plan for contingencies, particularly in remote legacy mines. A closed mine in northern Canada with no permanent on-site personnel had a simple water balance model that was effective for decades to inform annual water treatment operations. In recent years challenging water quality and more stringent effluent quality criteria has strained those treatment operations and led to more water being stored. Additionally, the region has experienced more precipitation and higher water levels, which have triggered emergency response activities. A calibrated probabilistic model was used to provide enhanced prediction capabilities and to identify key sensitivities in the water balance for monitoring. A several-year case study shows the value that this modelling tool provided for mobilizing personnel and performing response actions, particularly the inclusion of probability paired with forecasted pond water levels. Annual drawdown targets were subsequently established which provided more certainty in scheduling of annual treatment operations

Mar 2, 2022

By W. G. Miller

A series of computer programs for the analysis and mapping of coal-related data has been developed at the Illinois State Geological Survey; these programs, known collectively as the Coal Data System, represent the latest achievements in computer processing of geologic data at the Survey. Building upon programs previously developed in the Survey's Computer Services Unit, they expand the scope of the computerized data base that the Survey has been using for analyzing coal-related data. The System was partially developed during a joint study by the Illinois State Water Survey and the Geological Survey entitled, ?Coal and Water Resources for Coal Conversion in Illinois.? 2 In that study the available coal reserves more than 42 inches thick in the two principal coal seams throughout the state were mapped. The System was used to calculate the coal reserves and to report the average number of tons of coal in place per square mile in each township (Figures 1 and 2). It also produced maps of the coal features of sufficient quality to be printed on material that was scribed as master copy for the printing of full-color 1:500,000 scale maps (see Figures 3 and 4).

Jan 1, 1975

By Jaroslav Briancin, Katarína Gáborová, María Florencia Márquez-Zavalía, Marcela Achimovičová, Ol’ga Šestinová, Pavel Škácha

Naumannite (Ag,Se), a silver selenide mineral, was first discovered in 1828. This study investigates the structure, morphology, chemical composition, and leaching kinetics of naumannite. Mechanical activation in a planetary ball mill increased its specific surface area, enhancing the leaching rate of silver in nitric acid (HNO3). The study found that mechanical activation significantly improves silver recovery.

Jul 1, 2023

By Javad Sattarvand, Milad Ghahramanieisalou

As new technologies are introduced to the mining industry, the challenges related to their safe assimilation and the potential changes they bring to mining techniques necessitate adjustments to the current operations. Predictive simulations are critical to understanding unforeseen scenarios and shifting costly changes from the operational stage to the design. The Digital Twin methodology has gained a lot of attention in recent years. Many industries, from manufacturing to engineering and even social sciences, are adopting this approach to understand better the complex systems they are working with. By considering the enormous expenses and risks related to a pilot project, DT could replace that by acting as a prototype in which realistic tests and simulations are carried out with close to zero cost. DT includes a data hub, simulation and analysis tools, and visualization platforms to enable appropriate designs and monitoring plans focusing on unknown areas. A few examples of DT's application in mining include fleet management, Mine-to-Mill optimization (especially D&B), geotechnical digital twin (gDT), etc. When developing regulations, testing the efficiency of the mine layout, design, and magnitude of the restricted area and its access points, human-machine interactions, risk identification, and management processes, examining the efficacy of control systems, and monitoring, DT could help speed up (or completely replace) the process in the physical world.

Jun 25, 2023