Search Documents

By Yi Luo

In a shearer longwall mining operation, the longwall bits are responsible for breaking into and chip-ping the broken coal blocks away from the coal face. However, underground observations have found that a large number of longwall bits are always working under various degrees of wear. Reduction of the bit wear could be realized by using better designed longwall bits and properly selected shearer operating parameters. A computer program has been developed to simulate the performance of the longwall bits. The shape of the bit head, the installation of the bits on the drum and the operation parameters are the information required by the program. Through the simulations, the main factors affecting the bit wearing process are identified. Suggestions are also made for improving the design of the longwall bits.

Jan 1, 1996

By A. Hajati

The main purpose of this study was to find the optimum values for factors affecting the Zn recovery rate using oxine or dithizone as a chelating agent collector during flotation in a Hallimond tube. Eight control factors, including four levels of pH, oxine/dithizone, corn starch, sodium thiosulfate, sodium citrate, sodium silicate, conditioning and floating durations were considered in a Taguchi experimental design technique. An L32 orthogonal array was applied to determine the signal-to-noise (S/N) ratio. Analysis of variance (ANOVA) was used to determine the optimum conditions and the most significant parameters affecting the reaction rate. Analysis of the experiments using the Taguchi approach indicated that pH had the highest contribution to the recovery rate of zinc oxide particles. The results showed that the recovery rate of zinc increased by 43.4 ± 3.0% and 24.9 ± 3.2% using oxine and dithizone, respectively, under optimum conditions with a confidence level of 90%.

Jan 1, 2010

By R. L. Loofbourow

SEVERAL categories of storage are used depending on capacity. Operational storage, which is small in comparison with the market, facilitates handling surges of a few hours' or a few days' duration. Seasonal storage, usually larger, permits accumulation of product during sea- sons when demand is low, for delivery when demand is high. In producing areas, large storage may permit production at a uniform rate, without waste or distress sale. Near large markets such storage increases the efficiency of transportation, allows a more extensive or higher grade market to be served, and affords protection against interruption in delivery.

Jan 1, 1959

By Nikhil Dhawan, Sanjay Pindar

The limited lifespan, ever-growing demand, and significant lithium and cobalt content are responsible factors for the immediate recycling of discarded lithium-ion batteries. Discharged batteries were dismantled, segregated, and size reduced to recover cathode and anode material. The active cathode material comprises LiCoO2 (65.8%) and LiMn2O4 (34.2%) and was carbothermal reduced with recovered graphite in a microwave furnace followed by water leaching and magnetic separation. A Box Behnken statistical experimental design is used for process optimization. Both cobalt and manganese report to magnetic fraction, whereas graphite and lithium carbonate report to non-magnetic fraction and solution crystal respectively. The final product comprises of cobalt 73% and manganese of 14% with process yield of 36% and saturation magnetization of 76 emu/g.

May 16, 2020

By Charles H. Wells

This paper describes a commercial installation of a sophisticated instrumentation and control system designed to maximize the performance of heavy medium cyclones. Samples of plant feed and its products were collected and analyzed for ash content so that measures of efficiency could be determined for plant operation under (1) manual control and (2) automatic (computer) control. The heavy medium cyclone control strategy and its digital computer implementation are discussed in detail. The sample results are analyzed and the economic benefits of automatic control are discussed. Results from the initial data sets quantify the economic benefits of automatic closed-loop control; viz, increased recovery and reduced clean coal variability have been clearly demonstrated.

Jan 1, 1981

By S. K. MONDAL, K. K. K. SINGH, S. Singh, R. K. TIWARY, S. K. Chaulya, G. C. MONDAL, R. S. Singh, T. B. SINGH

In this work, a comprehensive field study was carried out to measure the background air quality status and identify the air pollution sources from opencast mines around a heritage site in India. Air quality modeling was conducted to envisage dust concentration due to existing and closed mines in the region. The air quality modeling exercise predicted that particulate-matter levels of PM10 and PM2.5 might increase in the ranges of 3.2 to 23.1 and 2.1 to 8.9 μg/m3, respectively, due to mining activities when some of the closed mines will be operated in the region without controlled emission. The predicted total PM10 and PM2.5 at the selected receptor locations were in the ranges of 86.39 to 194.89 and 34.82 to 99.55 μg/m3, respectively. Adequate measures were suggested to control air pollution from mining activities, and an intelligent dry fog system was designed to suppress dust emission efficiently from mineral processing plants and opencast mines. The developed system has special features for facilitating eco-friendly mining.

By E. Woodburn, H. W. Smith, M. C. Fuerstenau, R. Putman

This paper presents a review of developments to date in computer control practice, based in large part on Canadian experience. The basic problem examined is that of stabilizing control; matters considered are control strategies, hardware and software aspects of system implementation, reliability, human factors, and economic results.

Jan 1, 1976

By Shiou-Chuan Sun

The froth flotation of coal, differing greatly from that of most minerals1-5, is not improved but rather impaired by temperatures higher than room temperature6-10 This phenomenon has long taunted us for an explanation. Gayle and Associates 8,9 reported the lack of relationship between their contact angle measurements and their flotation of American coals under various temperatures. Bailey and Whelan6 stated that the viscosity of flotation reagents, offering some clue for their flotation of British coals at low temperatures, could not be put forward as an explanation either in whole or in part for the effect of temperatures on coal-flotation. In this paper, a froth hypothesis is proposed to explain the flotation behavior of coals under various pulp temperatures. Test work involved the flotation of coals and the frothing of reagents.

Jan 1, 1966

By Arash Nikvar‑Hassani, Timothy Batchler, Lianyang Zhang

Recently, a new hybrid geopolymer/biopolymer (GP/BP) cementitious material was developed for improving the performance of pumpable roof supports in underground mines. This study demonstrates the application of the hybrid GP/BP cementitious material and validates its effectiveness in full-scale. In this regard, eight (8) full-size (0.61 m diameter and 1.52 m height) cribs were produced in collaboration with Minova International Ltd and tested at the National Institute for Occupational Safety and Health (NIOSH) Mine Roof Simulator (MRS) Laboratory. These full-size cribs were produced with different material configurations to evaluate the effect of water to solid (W/S) ratio, Portland cement (PC) content, and BP dosage. The results demonstrated and validated the effectiveness of the hybrid GP/BP cementitious material in increasing the peak and residual bearing capacities of pumpable cribs and eliminating the issue of deterioration when exposed to air compared with the conventional Portland cement/fly ash (PC/FA) cementitious material currently used in practice. On average, the peak uniaxial compressive strength (UCS) and the highest residual UCS after peak of the full-size cribs produced from the hybrid GP/BP cementitious material are 1.90 and 1.33 times of those of the PC/FA-based full-size cribs by one company and 2.32 and 1.66 times of those of the PC/FA based full-size cribs by the other company, respectively.

Feb 6, 2024

By Frank J. Skudrzyk, Vladimir F. Petrov

In compliance with the current Russian environmental legis­lation, possible impact of industrial activities on the environment is restricted by acceptable limiting values (maximal allowable concentrations - MAC) of individual chemical substances in the natural environment - water, atmospheric air and soils. These norms have federal status and are valid for the whole territory of Russia. Disposal of the substances, for which no MAC is estab­lished, is forbidden by the law. Many gold mining companies use cyanide in precious metal recovery. This paper overviews the Russian experience in pro­tection of natural water reservoirs from technogenic impact of cyanic technologies. Major toxic compounds, contained in liquid and solid rejects from hydrometallurgical treatment of gold ore using cyanidation, are cyanides (CN), thiocyanates (SCN) and cyanide metal com­plexes. Unlike western classification of various cyanide types, in Russia any inorganic cyanide compounds (simple and in com­plexes with metals), with the exception of iron cyanide com­plexes, are considered toxic and the acceptable limiting value is established for them. MAC is 0.05 mg/I for fish reservoirs and 0.1 mg/I for drinking water. For iron cyanide complexes MAC is 0.15 mg/I for fish reservoirs and 0.25 mg/I for drinking water. Russian norms for thiocyanates are practically as rigid - the acceptable limiting value for them in fish reservoirs is at the level of 0.07mg/l (0.15 mg/I for potassium thiocyanate) and for drinking water - O. lmg/1. Norms for metals are established on the basis of total content regardless of the form in which they are present in water - as cations or complex ions. It should be noted, that in case several toxic compounds of the same limiting value (for cyanides, thiocyanates and base metals the limiting value is toxicological) are present in water. Their allowable concentra­tion is calculated as the sum of actual concentration of each com­pound, divided by the corresponding acceptable limiting value, with the result not to exceed one (compounding effect). Differences in cyanide classification and the necessity to include thiocyanates dictate different analytical methods. This, in a number of cases, results in certain discrepancies in analytical results. Until recently chlorination was used as a basic process of detox­ification of wastewaters. Calcium hypochlorite powder or hypochlorite pulp, prepared of lime milk and chlorine shipped to the plant, were used as a reagent. Chlorination is an efficient method: it allows to completely destroy plain and complex cyanide, in addition to iron complexes, and thiocyanates. A good example of high efficiency chlorination can be found at the Mnogovershinniy mill near the Okhotsk Sea located in the salmon spawning area, for which we designed an automated chlorination plant for tailings dam. Since plant start-up ten years ago, the required concentrations of cyanides and thiocyanates have been kept at the MAC level required by environmental regulatory agen­cies and no harmful affects on ichthyofauna has been reported. One major drawback of chlorination is high cost of the major reagent, as well as secondary contamination of detoxified waters by chlorides. Secondary contamination by chlorides becomes obvious in the course of detoxification of wastewaters of com­plex composition, which require increased reagent consumption. Recent changes in economic conditions in Russia caused the necessity to direct efforts to reduce the costs of precious metals recovery, and in particular, wastewater treatment. We have con­ducted certain work in this direction and obtained positive results. We hope that our experience described below will be of interest to other specialists particularly taking into account the current low gold prices.

Jan 1, 1998

By T. W. Camm

Some of the defining characteristics of narcissists include a grandiose sense of self-importance, preoccupation with success and power, a sense of infallibility, and a supreme confidence in their ability and intelligence. Ironically, many of these characteristics are rewarded in business organizations, which may explain why there seems to be so many narcissists in management positions. Assuming we will be dealing with narcissists throughout our career, it makes sense for us to understand what makes them tick, and more importantly what we can do to work with them in a constructive manner.

Feb 23, 2014

By Robert J. Garino

Around two-thirds of world silver mine production comes from mines where the majority of ex-mill revenue is obtained from other metals. In this talk I will illustrate the importance of this output of silver as a by-product of the mining of various base metals. I will also consider the impact of relative changes in base and precious metal prices on mill-head revenue, and therefore, on production decisions. During the latter half of 1982 improving silver prices encouraged re-openings at several base metal mines. Thus some production of lead, zinc and copper can be regarded as partly conditional on the prevailing silver price. Conversely, a good deal of silver production can be considered to be independent of the silver price and dependent on the production of some base metal. It is the degree to which the value of silver mined affects the revenues of nominally, base metal, producers that is the central concern of this presentation.

Jan 1, 1983

By Rodolfo Lagos, Nicos Pfeiffer, Ben Harding, Clayton V. Deutsch

This paper documents a probabilistic resource modeling workflow for the Round Mountain epithermal gold deposit. The set of categorical and continuous variable simulated realizations provides a model of variability and uncertainty given the current orebody knowledge. These realizations can be used to quantify and understand expected deviations in reconciliation during mining and provide a more accurate measure of expected gold than an estimated model. Gold mineralization at Round Mountain is primarily contained within tertiary tuff units, which dip gently to the west and thicken towards the southern part of the orebody. Domain boundaries are modeled as combinations of lithology and alteration; alteration domains are constrained to be within the tuffs. Large-scale geologic uncertainty is strongly influenced by parameter uncertainty, particularly the input histogram. The spatial bootstrap characterizes prior global uncertainty in the input histogram for categorical and continuous variables. Categorical models are generated using hierarchical truncated pluri-Gaussian (HTPG) simulation. Continuous variable simulation is carried out within the simulated domain boundaries using trend models to account for non-stationarity.

Aug 19, 2023

By Baolin Qu, Jingxin Wang, Cuncang Xu, Bing Wu, Mingyu Zhong

With the development of the coal mine regulation regime, the situation of coal mine safety production in China has continued to improve. However, coal mine accidents have not been fundamentally eliminated; constantly learning from historical accidents can make mining work safer. Therefore, to better understand the coal mine accident characteristics, this study analyzes the tendency of coal mine safety accidents from multiple perspectives, among which all accidents after the establishment of the State Administration of Coal Mine Safety in 1999 are the top priority. The results show that strict national policy, technological progress, and reasonable coal prices are conducive to the safe development of mines. On the contrary, high-intensity centralized production will lead to frequent accidents in the peak season of coal production. In addition, the type of coal mine ownership will have an indirect impact on the occurrence of coal mine accidents. The research results not only play a positive role in the prevention and control of coal mine accidents in China but also have reference meanings for the safety production of coal mines in other countries in the world.

Dec 28, 2022

By L. John Minnick

A revised and expanded edition of a previous paper** dealing with reactions of calcium and magnesium oxides and hydroxides with pulverized coal fly ash is presented. Lime-fly ash specimens were cured at constant temperature and subjected to X-ray diffractometry, differential thermal analysis, pozzolanic reactivity tests, and microscopical investigations. Bars of limefly ash were subjected to cycles of wetting and drying, and measurements of length change were recorded. A discussion of variations within and among types of lime and types of fly ash is presented. The nature of the pozzolanic reaction is reviewed, particularly as related to compounds which are used up and formed during the aging process. The relationship between the pozzolanic reaction and the resultant physical properties of the mixtures is examined.

Jan 1, 1968

By Gregg J. Hodges

The Stillwater Mining Company, a partnership of The Pittsburg & Midway Coal Mining Co. and Manville Corporation, began commercial production of flotation concentrates from the western hemispheres' only primary platinum palladium deposit at Nye, Montana in March 1937. In the fall of 1987 an integrated pilot plant testing campaign of electric furnace smelling and oxygen? blown converting confirmed the feasibility of further upgrading to semi? refined matte or 'white metal". In the summer of 1990 the production smelter was brought on-line at Columbus, Montana. This paper describes the technology transfer from the pilot to the production smelter. Emphasis is placed on flowsheet development and the scale factors between the test and production furnaces and gas cleaning plants. The metallurgical results of the pilot plant and of the early months of production of the commercial works are also compared.

Jan 1, 1991

By J. Kretschmann, R. Amiri

"The Sangan iron ore mines (SIOM) in Iran are located in a remote area near the Afghanistan border. The SIOM deposit contains a geological resource of 1.1 Gt (1.2 billion st) of mostly magnetite with an iron (Fe) grade ranging from 27 to 61 percent. The Iranian government plans a stepwise development of SIOM in cooperation with private companies to satisfy the growing demand of the Iranian steel industry. Sustainable development is an influential ethical concept in mining all around the world. However, a successful realization of a sustainable development plan is not possible without a foundation on the core values and regarding the specific circumstances of the individual mining country. This paper introduces SIOM and describes sustainable development activities undertaken during its development. From the early stages, these activities have been realized to secure the acceptance of the stakeholders in the region. To evaluate their effects, indicators were filtered to the ones with the highest priority for the stakeholders. Moreover, Islamic values and Iranian regulations and their influences on SIOM were analyzed.Mining industry in Iran The Islamic Republic of Iran holds 68 types of minerals, including salt, sand and gravel, gypsum, chrome, lead, zinc, copper, coal, gold, iron, etc., with 33.5 Gt (37 billion st) of proven reserves and more than 51.7 Gt (57 billion st) of potential resources. Iran is ranked among the 15 major mineral rich countries (1). In accordance with the statistics published by Statistical Center of Iran (SCI), there were 5,316 active mines and 84,922 employees in the whole country in 2012-2013 (2) and, according to the statistics published by Central Bank of Iran (CBI) in 2011, the share of this sector in the gross domestic product (GDP) of the country was 1.2 percent (3)."

Jun 1, 2016

By Natalie White, Joel Asp, Allyz Kramer

"Minnesota has robust reclamation standards and have proven results in the taconite mining industry. Reclamation of overburden spoils, lean ore spoils and fine tailings from taconite production has generally been successful on the Iron Range, using a low input standard reclamation practice. Success at reestablishing vegetation on these landscapes is likely due to fairly favorable chemical and physical properties (e.g., few limitations due to acidic generating materials, metal toxicities and water and nutrient holding capacities). However, coarse tailings reclamation has proven more difficult, presumably due to lower nutrients and challenges with moisture holding capacities. Research efforts conducted since 1990 have struggled to develop a reclamation strategy for coarse tailings that meets the Minnesota Mineland Reclamation Rules, Chapter 6130. However, new breakthroughs in scram mining technologies are producing fine and coarse tailings that have not been encountered nor reclaimed in northern Minnesota. Scram mining in Minnesota is defined as those mining operations that produce natural iron ore concentrates. Innovative research is underway to investigate and determine successful reclamation strategies to reclaim scram mining tailings from these scram mining operations. The research program is conducted through collaboration with SEH, Prairie Restorations, Inc. (PRI) and Mining Resources, LLC with funding support from the Iron Range Resources and Rehabilitation Laurentian Vision Partnership minescapes grant program.The research program was divided into three phases:Phase I. Bench-scale testing to identify successful treatments to reclaim and restore scram tailings through evaluating surface soils amendments, viable seed mixes and plant germination, growth and densities. Phase I was completed in early 2015.Phase II. Field-scale pilot trial to test larger scale effectiveness of the treatments deemed successful in Phase I and test various vegetative assemblages and planting techniques focused on the unique challenges with scram tailing basins. Phase II was completed in late 2016 with a summary monitoring report.Phase III. Produce a technical report of results for the research undertaken in this study, as well as compile prior reclamation results used during previous Minnesota iron mining reclamation projects on tailings basin applications. Phase III was completed in 2017 with a summary monitoring report and recommendations."

Jan 2, 2018

By Brian H. Kaye

Efficient design of grinding circuits for efficient production of ultrafine material requires rapid feedback of information concerning the fineness of material leaving the grinding device. Generating this information requires efficient sampling and adequate rapid characterization of the material leaving the grinding machinery. Recent developments-in electrooptic inspection of dry end wet material leaving a grinding device are critically reviewed. New methods for characterizing ultrafines are discussed. A rapid operating automated cybernetic (intelligent) permeability device for automatic control of grinding circuits using Blaine index and other fineness indices is described.

Jan 1, 1983

By Michael L. Clar

Reclamation of surface mined lands has two basic objectives: (1) the elimination or abatement of undesirable environmental conditions, and (2) the restoration of mined land to its former or more productive uses. This paper addresses some of the planning concepts and site factors that influence the selection of suitable land uses for surface mined lands. Three planning concepts included in the discussion are: (1) mine land planning, (2) comprehensive land use planning, and (3) environmental site planning. The site factors that will influence the selection of an appropriate land use have been grouped into three categories: (1) legal, (2) geographic, and (3) natural. The natural factors are further subdivided into three groupings: geomorphology, soils, and climate.

Jan 1, 1981