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By Michel Grenier, Mahendra Gangal

Two methods used to measure the exposure of mine workers to diesel exhaust particulate were compared. One method was developed by the U.S. Bureau of Mines and the University of Minnesota's Particle Technology Laboratory. The method which was originally developed for use in coal mines is a size selective sampling technique. The other method uses an “ashing" approach to assess the exposure to diesel particulate. This second method is based on the principles of sampling according to the ACGIH respirable dust sampling criteria and the use of a silver membrane filter as collection substrate. Because a silver membrane filter is used, both respirable combustible dust (diesel particulate) and respirable silica can be measured from one sample. The comparison study took place in a Canadian lead-zinc mine during tests which were primarily designed to evaluate the gaseous and particulate emissions characteristics of new diesel engine technology. The study has shown that under the test conditions encountered, some differences were observed between the results as obtained by the two methods. These differences seem to depend on the characteristics of the respirable dust found in the work- place, i.e., size and composition. The impact, on sampling and analysis of diesel particulate, of the proposed guideline (ACGIH) for a TLV® of 0.15 mq/m3 is discussed briefly.

Jan 1, 1997

By Chao Zhang, Wenhao Xia, Jianxin Fu, Ling Yu, Weidong Song, Yang Li

Sanshandao Gold Mine is the only undersea metal mine in China. To deal with the collapse and pumping of stopes and roadways caused by complex ore-rock occurrence conditions, the mine conducts filling and sealing of some areas, and the remaining ore reserves will be mined after treatment. Therefore, it is urgent to evaluate the stability of rock masses, fault fracture zones, and aquicludes during the secondary mining process. In this study, displacement and microseismic methods are employed to monitor rock deformation and fractures. Additionally, FLAC3D was used to simulate the process of secondary mining, reproducing the evolution of stress fields, displacement fields, seepage fields, and plastic zones at different mining stages. The combination of numerical simulation and on-site monitoring verification demonstrates that the deformation of surrounding rock presents a rapid growth at the initial stage of mining, followed by a gradual decrease in the growth rate, and finally tends to stabilize; the fracture zone area at the 151–159 exploration line on the − 320 m level (near the 7# and 8# stopes) exhibits poor stability, and monitoring measures should be strengthened; the deformation value of the aquiclude is less than the deformation value of I protection level in the Code for Design, the impact of secondary mining on the aquiclude is limited; fault and fracture zone deteriorate rock mass stability, and their impact is related to their spatial locations. Hanging wall fault has a more significant impact on the settlement of the aquiclude, while the footwall fracture zone has a greater impact on the development of the plastic zone.

Feb 21, 2024

By Crystal Poon, Paul Matlashewski, John Morkeh, Kathryn Dorfschmidt, Jose Carvalho, Chad Williams

Rockfall hazards are ubiquitous in mining environments making their control critical for safe mining operations. The complex processes involved in rockfall events necessitate a probabilistic modeling approach with well-calibrated material properties. The controls designed to mitigate rockfall hazards need to be reliable, efficient, and safe to deploy to meet the constraints present at an active mine. This paper presents an innovative solution to rockfall at Rio Tinto’s Bingham Canyon Mine. The solution incorporates the site-specific calibration and creation of a predictive rockfall model with the design, field testing, implementation, and monitoring of the rockfall controls.

By H. Lyn Bourne

The is the 14th consecutive year for this column and the 13th in which the royalty data have been tabulated. Some holes still exist in the list of royalties that readers hopefully will fill. Construction aggregates - either sand and gravel or crushed stone - are the most common mineral commodity. In spite of their pervasive use nationwide, royalty information for these commodities has been difficult to acquire from some states. Readers can help. Share information about these missing states and next year there will be fewer states without information. Dennis Bryan sent a copy of a report, "Regional Appraisal of Mineral Materials: Carson City District, BLM." The report was authored by real-estate appraisers. It contains more than 50 references to leases of various construction materials in Nevada and nearby states. It gives a thumbnail sketch of each lease and is a good reference. However, the authors erroneously imply that the royalty rate and the in-place value are the same. Several of this year's new entries come from the report. However, the royalties for landscaping materials vary from state to state and by rock type. Some boulders used for landscaping in Nevada have a royalty reported at $1.10/t ($1/st). At the other extreme is lava from Idaho. Used for the same purpose, it has a royalty range of $11 to $18.70/t ($10 to $17/st). Chuanming Tian of Beijing, China has shared some information about the changing mineral royalty policies in China. China first implemented an oil and gas royalty in 1984. In 1992, the government expanded that to include iron ore. In 1994, the royalty policy was extended to all mineral commodities. At the same time, the royalty rate for iron ore increased tenfold.

Jan 1, 1995

By Pramod C. Thakur

During the past ten years, the US coal industry has experimented with various ways to extract methane from coal seams. Drilling long horizontal boreholes in solid coal from mine workings and vertical gob degas boreholes are becoming standard techniques for methane recovery from coal seams. Prime motivations for such work have always been safety and productivity in mines, but the commercial value of gas so produced is encouraging utilization. The paper reviews various ways to produce methane from coal seams and discusses some utilization projects extant in the industry.

Jan 1, 1984

By W. Z. Choi

In our previous work, a population balance model describing the simultaneous processes of size reduction and mineral liberation has been developed. The experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, the estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple composite class model has been developed. Emphasis is placed on the direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

By J. G. Pippenger

The Coteau Properties Company's Freedom Mine is a surface lignite mining operation located near Beulah, North Dakota. Coteau, a wholly owned subsidiary of The North American Coal Corporation, produces more than 13.5 million tonnes per year, ranking it among the largest mines in North America. In 1993, Coteau ranked seventh in terms of annual coal sales, becoming the largest mine outside the Powder River Basin of northeastern Wyoming. However, for the Freedom Mine to stand among these Powder River heavyweights, Coteau over-came several obstacles, including a coal seam with three quarters the heating value and overburden to coal ratios three times higher than the Powder River mines. Coteau's ability to compete has been built around a program of continuous productivity improvement, cost efficiency, and innovation. This report highlights a few of the major improvements implemented in recent years.

Jan 1, 1995

By H. Wilcox, M. Prichard, Y. P. Chugh

Environmental considerations related to the disposal of coal combustion byproducts (CCBs) and the impacts of deforestation associated with the harvesting of timber for utilization as roof supports in mines should become more severe in the future, as landfill space and suitable timber reserves become more scarce. To help address these concerns, lightweight artificial supports, such as post and crib elements, that use large percentages of coal combustion byproducts as aggregate have been developed for use in underground mines. These structural products show equal or better engineering characteristics than timber, and they have the potential to replace timber support in underground mines. CCB-based ultralight structural material (ULSM) has also been developed and commercialized for use in the construction of ventilation stoppings in underground mines. The bulk densities of these blocks range from 0.40 to 0.64 g/cm3 (25 to 40 lb per cu ft) with more than 75% CCBs. Efforts are also given to develop and demonstrate large volume CCB-based subgrade improvement technique for road construction. Soil treated with SIUC fluidized-bed combustion (FBC) fly ash developed an immediate bearing value exceeding 25% with a swelling strain of less than I %, which is greater than untreated soils, and met Illinois Department of Transportation (IDOT) standard specifications. In this paper, development procedures, engineering characteristics and beneficial uses of CCB-based structural products are given.

Jan 1, 2002

By Bill A. Hancock

In Situ leaching for the recovery of uranium from low grade sandstone deposits is one of the newest technological advances in the mineral industry. It is rapidly developing into a commercially feasible mining system which has economic, environmental, and social advantages over conventional mining systems. Because of the current uranium shortage, development of In Situ leaching into a sophisticated system has gained new impetus. In Situ leaching will become an important mining technique in the future, which will greatly help to supply uranium for our nation's energy heeds. In this paper, I will be giving an overview of the merits of the system, as well as the technology, problems, and research in solution mining of uranium.

Jan 1, 1977

By S. S. Hsieh

The important carboxylic acid components of tall oils were tested individually as phosphate flotation reagents. These included C18 unsaturated fatty acids and C10 to C18 saturated fatty acids and resin acids. These experiments were conducted to evaluate such factors as the degree of unsaturation, hydrocarbon chain length, isomeric form, side-group modification, and cyclic structure. The effects of mineralogical characteristics on flotation response also were considered. The results of this systematic evaluation provide guidelines for selecting efficient substitute reagents and also provide fundamental data for further research on improved flotation technology.

Jan 1, 1980

By John D. Morgan

The U.S. economy annually needs over 4 billion tons of new mineral supplies. The value of domestically produced energy and processed materials of mineral origin exceeds $175 billion annually, but domestic production of both raw and processed minerals is not keeping pace with demand.

Jan 1, 1974

By Anthony W. Garson

Good morning, ladies and gentlemen: It is a pleasure to be here this morning as a representative of Dean Witter Reynolds; one of the foremost international investment firms in North America. My colleague, Hugh Wilmer (who will be speaking to you a little later), and I are involved as research analysts in the research and writing of published reports containing recommendations on the buying or selling of North American and South African gold and silver mining shares. Our talk this morning will focus on the gold mining operating costs of North American and South African gold producers. However, I am not going to bore you with reams of statistics on the operating costs of large numbers of gold mining operations; how meaningful would this data be to you? Instead, I will discuss what the investor should look for, and how he should use this knowledge in making his investment decision.

Jan 1, 1984

By G. R. Brunskill

The molybdenite flotation plant at Magma Copper Company, San Manuel concentrator has been in operation since 1956. In January of 1980 the plant was converted from a hydrogen peroxide - ferrocyanide process to the current sodium cyanide - sodium hydrosulfide process. This paper is an operational review of Magma Copper Company's molybdenite recovery circuit, column cell flotation experience and use of on- stream x-ray flourescence analysis.

Jan 1, 1985

By Yuanyuan Wang, XUEWEN WANG, Jinzhi Wei, Ligang Wen, Muxin Jia, Zhengyao Li

The abstract discusses the use of disodium carboxymethyl trithiocarbonate (D8) as an effective depressant in the flotation separation of stibnite and pyrite. The study investigates the mechanism behind D8's selective inhibition of pyrite, utilizing techniques like micro-flotation experiments, contact angle measurements, infrared spectroscopy, adsorption capacity analysis, and zeta potential measurements. The findings reveal that D8 physically adsorbs onto both pyrite and stibnite, but its adsorption capacity on pyrite is significantly higher. This adsorption enhances the hydrophilicity of the pyrite surface, hindering the adsorption of the collector and effectively depressing pyrite flotation, while having minimal impact on stibnite floatability.

Mar 14, 2022

By A. S. Atkins

The interest in the use of micro- organisms in the leaching of sulphide minerals has been traditionally exploited as a scavenger process for the recovery of valuable metal by- products from waste ore dumps. Environmental concern on sulphur emission from conventional pyrometallurgical plants together with the cost of stack cleaning systems to comply with legislative control also indicate baccerial leaching to offer a low cost treatment for the processing of sulphide minerals. The paper describes the effect and limits of relatively coarse particles on the complete leaching of pyrite and its importance to the practical application in dump leaching operations of sulphide minerals. It has also been demonstrated that static leaching techniques have encouraging economic potential for process plant operations compared with agitated leaching systems.

Jan 1, 1984

By F. Seymour

A modified 3D Lerchs-Grossmann (LG) graph tree algorithm is presented that generates the complete set of nested maximum valued pits in a single run. This modified LG algorithm looks at the relative strength (average value) of the branches (groups of blocks). Pointers are allocated and pruned until there are no members of weaker (lower average value) branches overlying members of stronger (higher aver-age value) branches. The final set of strong branches are listed in order of decreasing strength. The pits they represent form the maximum valued convex hull for a single variable pit limit parameterization. A description of the algorithm is given along with examples of how it has been applied at Newmont.

Jan 1, 1995

By Krawiec Alfons

The threat of rock bursts along with the danger from methane gas and coal dust explosions belongs to particularly dangerous phenomena in Polish pit-coal mines. This phenomenon results mainly from the physical-mechanical properties of the rock mass as well as the geological-tectonic structure of the Upper Silesian Coal Basin. In the postwar years in Polish coal mining thanks to a multi- directional activity, a decrease of rock bursts and their effects has been noted. For example, the number of rock bursts reported in 1965 amounted to 71 in comparison to only 23 in 1974. The ratio of rock bursts calculated for 100,000 tons of coal extracted from rock bursting strata amounted to 0.08 in 1965; however, in 1974 it amounted to 0.023 /Fig. 1/. These results were obtained in face of a continually growing potential threat from rock bursts caused by the systematic increase of extraction from rock bursting strata, exploitation at gradually greater depths along with the extension of exploitation into deposits enclosed in different types of pillars and other parts of deposits surrounded by workings. Despite the achievements of science and mining practice in this field, this threat has not yet been fully studied and controlled as it should be, As a result, research on preventing rock bursts is being continually widened in Poland. This research has a complex, multi-staged and long-range character. Theory, laboratory and field work in the mines are working on a solution to the problem.

Jan 1, 1976

By A. K. Gangopadhyay

This paper discusses the effect of grinding media composition, mineral type and slurry environment on the wear rate of various grinding media (balls). Sufficient wear data have been obtained and correlated with the modes of wear determined from examination of the ball surfaces using scanning electron microscopy. Five modes of wear have been identified to be operative under certain slurry conditions for the various ball compositions studied.

Jan 1, 1984

By M. A. Giralico

A new generation of hydraulic efficient pumper and auxiliary impeller designs is the result of an extensive research program focused on improving the overall performance of optimized SX/EW plants. Combined with the proper scale-up, these optimized designs will greatly reduce aqueous and organic entrainment losses, reduce or eliminate air entrainment and crud formation, enhance mass-transfer and maximize the overall copper yield. Currently, these new pumper and auxiliary impellers are installed full-scale in numerous plants ranging in flow rates from 90 to 15000 G.P.M. and developed heads up to 51 inches. Operational results reported by the independent metallurgist at each processing plant are reporting the lowest entrainment results in the industry. Further R&D has just been completed on a new mixing configuration that separates the systems mixing and pumping requirements. Results from the system pilot test document further improvements in reduction of both chemical entrainment and crud formation, while keeping mass transfer stage efficiencies.

Jan 1, 1998

By J. A. Herbst

Until the past decade, the energy-size reduction relationship was the dominant form of mathematical model used in the description of tumbling mill grinding processes (1,2). Typically, in these models some single measure of product fineness (e.g. the 80% passing size, the size modules, the specific surface area) is chosen as the dependent variable and the energy input per unit mass of material being ground acts as the independent variable. In some instances these models have been useful for the correlation of experimental data, but, invariably, they have been found to be inadequate for meaningful process simulation. During the last decade considerable advances have been made in the development of phenomenological grinding models derived from population balance considerations (3-7). In these models a set of dependent variables is employed, corresponding to the set of mass fractions which constitute the product size distribution, and energy input is abandoned in favor of "time in the mill" as the independent variable. The phenomenological models have been shown to provide accurate simulations of the entire size distribution of ground products produced in batch (8-10), locked cycle(11)and steady and unsteady state, open and closed circuit continuous grinding(12,13).

Jan 1, 1973