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By M. K. Mohanty

A modified coal flotation characterization procedure, referred to as the Advanced Flotation Washability (AFW) technique, has been developed which, compared to traditional procedures, provides a more accurate prediction of the optimum separation performance achievable by a froth flotation process. The AFW procedure uses a vertically-baffled flotation column which provides enhanced selectivity among particles of varying degrees of hydrophobicity due to a plug-flow environment and an improved carrying-capacity environment. In fact, the separation performance of the traditional procedures was enhanced by increasing the possibility of operating under improved selectivity conditions. The separation performance provided by the AFW procedure was superior to that obtained from multiple cleaning stages using commercially-available flotation columns under both kinetic and carrying-capacity limiting conditions.

Jan 1, 1997

By N. O. Lotter

Studies investigating the evaluation errors in laboratory scale flotation tests for platinum-bearing Merensky Reef in the Bushveld Complex, South Africa, have constructed a quality control model to assure a 95% confidence in the attested data. Specialized knowledge of the mineralogy of the platinum-group elements (PGE), together with acquaintance of evaluation models, validate a systematic checking of the sub-processes of the testwork. These include determination of minimum mill feed sample size, assay head reference distribution, mass balance checks, and specialized sample preparation of flotation test products prior to analysis. A flow schematic of this quality control model is proposed, with an example of test data that produce an error in the metal balance of 0,2% after rejection of outlier data.

Jan 1, 1995

Mineral Resource Technologies(MRT) and Michigan Technological University (MTU)finalized an agreement that permits MRT to offer an advanced carbon removal technology process for coal fly ash from an ash residue generated by utilities. The agreement encompasses the dominant existing US patents using a wet process for fly ash enhancement. The wet process for coal beneficiation of a fly ash product involves four steps. First, a slurry mixture is formed of a fly ash material and a liquid. Second, gravity is used to separate and collect a first-material fraction of the fly ash, having a density less than the liquid. This is done by skimming off the flotation slurry material.

Jan 1, 1996

By Siyu Song, Yanhong Wang, Guohua Gu, Linbo Huang

In this study, the effect of cations, Na+ and Mg2+, in saline water on copper flotation in the presence of calcium bentonite was investigated. It was found that as the concentration of NaCl was increased, the copper recovery initially decreased and then increased to above 99%, while the copper grade initially increased and then decreased. In contrast, as the concentration ofMgCl2 was increased, the copper recovery continuously increased, while the copper grade continuously decreased. The variation of copper recovery and grade was mainly attributed to the synergistic effect of pulp rheology and flotation solution chemistry. The underpinning mechanisms are the compressing electrical double layer and ion-exchange interaction between saline water and bentonite, which occur at the same time. Using salinewater slightly affected the pulp rheologywith a decrease in copper recovery at low NaCl concentration. Increasing the concentration of cations in saline water might even facilitate the flowing out of exchangeable cations, especially divalent cations, from the interlayer space of bentonite to the solution, resulting in the decrease of copper grade at high salt concentration.

Sep 10, 2020

By E. R. Bauer

The trend in underground room-and-pillar coal mining is to employ remote-control continuous mining machines and extended cuts, 12 m (40 ft) deep or more. This system of coal extraction, adopted by over 435 mines, can create additional worker-safety hazards. To address the ground control and worker-positioning hazards, a combination of statistical analyses and numerical modeling was conducted. Initially, the reported roof-fall incidents and fatalities were reviewed to delineate the ground-control hazards. Then, the application of the Coal Mine Roof Rating (CMRR) for estimating safe extended-cut depths was evaluated. Finally, computer modeling to predict roof displacements during extended-cut mining was completed. The paper describes the results of these studies and their impact on the safety of extended-cut mining.

Jan 1, 1999

By MANZOOR ALI BROHI, IZHAR MITHAL JISKANI, Atta Ur Rehman, SHUAI HAN, MUHAMMAD TARIQ, NIAZ MUHAMMAD SHAHANI

A thorough improvement in mine safety is contingent on many factors that require scientific decision-making for selection and prioritizing of important factors for safety improvement. Their analysis using an established scientific method can improve mines’ safety conditions and assist the administration for informed decision-making. This research establishes a mine safety evaluation index and proposes an integrative model based on the entropy weight and grey clustering methods. In the evaluation index, 27 significant factors of safety are identified and categorized into 7 criteria. The proposed evaluation system analyzes all indicators according to Pakistan’s current mine safety situation and their significance for potential safety improvement in the future. Results reveal that current safety practices are outdated due to a lack of mechanization in the mining industry and minimal capability of the management to achieve the desired safety targets. Appropriate safety policies and safety education are missing in the daily working environment. The lack of overseeing the execution of safety operations and the lack of ambition and strong work ethic workers contribute to the paucity of mines’ safety conditions. The prevention and control systems to manage risks and hazard are not in place, and the working environment in mines remain difficult. Therefore, to have enhanced mine safety, important factors can be addressed in chronological order, as presented in this paper. The proposed methodological approach can be applied to other prioritization applications to analyze the indicators and determine the appropriate management strategies.

Jun 14, 2021

By E. Bloomstein

The Lone Tree gold mine is located about 4S kilometers east from Winnemucca on the west flank of Lone Tree Hill in Humboldt County, Nevada. The deposit occurs at the north end of the low, rolling Havallah Hills and is about 1 kilometer south of Interstate Highway 80, in sections 11 and 14, Township 34 North, Range 42 East, Mount Diablo Base and Meridian (Fig. 1). The Lone Tree deposit is outside of any previously established mining district and all lands are owned or controlled by Santa Fe Pacific Gold or affiliated companies.

Jan 1, 1993

By C. D. Iles

The philosophy used in designing and writing Duval's Sierrita mine design programs is discussed. The Sierrita Incremental Design system (SID) is reviewed with emphasis on Pushback Extraction Design (PED). FED is a method by which predesigned pushbacks are sequenced into an optimized period-by-period design that can be directly utilized in daily operations as well as intermediate and long range planning. The advantage of SID is that it provides a practical, mineable open pit design. PED is not a theoretical design system; it is in operational use.

Jan 1, 1981

By Remi Tremblay

This paper describes the laboratory study which permitted an exploration of high grinding ball consumption in the secondary open circuit wet grinding mills at the Sidbec-Normines plant, Port Cartier, Québec. Corrosion undoubtedly exists but is of minor importance. Abrasion resulting from the physical nature of the company's iron concentrate is the main reason for the high ball wear. It was found that at least 30% reduction in ball consumption is possible by decreasing attrition grinding through the use of lifters in the mill. At the industrial level this would entail more lifters and/or higher lifters in the mill linings.

Jan 1, 1984

By R. Wild

[When a blast furnace has a certain defined burden and is operated under fixed conditions of blast temperature, etc., the fuel efficiency is determined by the extent to which the reducing gases can remove oxygen from the burden in the furnace stack. This is determined by two distinct factors: 1) The uniformity of gas-solid contact, and 2) The ease with which oxygen can be removed from individual pieces of burden. This latter is often called burden reducibility. When burdens were poorly prepared the first factor was by far the most important and a study of the reducibility of individual lumps was of rather academic interest recent years good burden preparation with emphasis on sized material has led to greatly improved gas distribution in the stack, and thus the second factor has become much more important and there has been a marked increase in interest in methods of measuring reducibility.]

Jan 1, 1964

By Koichi Nishimura

Japan's coal reserves are estimated at 8,583 million tons (according to the materials on X World Energy Conference,. 1976). Japan is a long island country in the shape of an elongated cashew nut whose top is pointing to the north and its lower tip is pointing to the west. And her major coal fields are located in the two extreme far parts of Hokkaido in the north and Kyushu in the south. On the other hand, Japan's major industrial center are located in the central part of the country far from either coal-producing areas. This fact places coal a great geographical disadvantage in comparison with petroleum whose refining bases are concentrated on the coastal regions virtually next to major industrial centers.

Jan 1, 1982

By E. W. Greig

This paper is an account of exploration for bauxite in the Amazon Basin, Brazil, and particularly of the discovery, exploration and development by Alcan of the Trombetas deposit so a general account of the Trombetas Project has already been published in E/MJ (Anon. 1975) to which the reader is referred for details on owner-ship, infrastructure and construction as well as the proposal for mining and treating the bauxite. It is impossible to consider the Trombetas deposits in isolation. A regional account of bauxite in and around the Guyana Shield and the northern portion of the Brazilian Shield is included and it is suggested that these deposits all formed during Tertiary time under similar conditions.

Jan 1, 1977

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a roomand-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90%. But, the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing oversprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99% and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber.

The dissolution kinetics of cobalt in iodine/iodide solutions was investigated using a rotating disc technique. Variables studied here included temperature, rotating speed, concentration of lixiviants, and pH of the solution. The overall dissolution reaction was found to be limited by mass transfer of tri-iodide through the diffusion boundary layer with Arrhenius activation energy of less than 16.2 kJ/mol (4 kcal/mol) over the temperature range, 2-42°C. The pH of the solution had little effect as long as the pH of the solution was less than 8. However, when the pH of the solution became greater than 8, the dissolution rate decreased dramatically due to passivation. The rate of dissolution was in good agreement with the dissolution model developed by the authors earlier.

Jan 1, 1994

By A. W. Khair

This paper presents an engineering approach to solve a complex ground control problem at reduced cost, allowing the mine to be operated safely and economically. The mine has experienced serious and complicated cutter roof problem in the entries. This cutler roof problem has delayed the advance of the entry development considerably and cost of these entries is very high due to the requirement of very heavy artificial supports. The analysis includes assessment of the cause of cutter roof and step by step action taken to improve the entry condition through appropriate longwall panel entry design and roof support system. The approach for solving the problem was two-fold: 1) to apply yield pillar concept in order to reduce the effects of in-situ horizontal stress in the roof strata and 2) to find an effective way to reinforce the roof strata and to support the fractured roof and avoid caving.

Jan 1, 1990

By Lennart Bergstedt

Boliden Aktiebolag, the prime base metal mining company of Sweden, annually treats some 11-12 million tons of sulphide ore in nine concentrators. Its first flotation plant was established in the early thirties for the complex Boliden ore. Since then, the number of mines and plants has gradually increased. Considerable effort has been devoted to the development of all phases of the technology of ore prospecting, mining, milling, smelting and refining. This has been necessary due to the complex and low-grade ores. The development of concentration has mainly been directed toward the arts of grinding and flotation. During the forties and fifties, open-stage fine crushing followed by two-stage grinding in rod and ball mills with cyclone classification was successfully introduced and used throughout the plants. The increasing cost of grinding media led to studies of an autogenous grinding technique as early as 1945. Basic test work commenced during the early fifties, with a. number of ores tested for pebble grinding. In 1956 a new pilot plant was built, with equipment installed for the continuous testing of pebble grinding and, later, for primary autogenous grinding of run-of-mine ore. The intensive test work showed that pebble grinding was feasible in almost all of the plants. At this early stage of testing, however, the merits of autogenous grinding could not be fully evaluated. As a. consequence the rod mill/ball mill grinding systems were converted to rod mill/pebble mill systems whereever possible. In parallel with the converting of grinding systems the development work concerning the merits of autogenous grinding went on. The major result

Jan 1, 1977

By R. Asamoah, P. Forson, W. Skinner, M. Zanin

Despite the seeming benefits decoupling pyrite and arsenopyrite minerals present in practice, little success has been achieved. The present study presents possible process routes for attaining selective flotation broadly capitalizing on differential oxidation between these minerals, and the use of a chelating collectors. The best performance was achieved with dithionocarbamate application following copper activation, yielding 81.4% arsenopyrite and 37% pyrite recovery. Preaeration followed by staged addition of xanthate produced 76% arsenopyrite and 31% pyrite recovery while reverse flotation of pyrite after H2O2 addition gave rise to rejection of 66% pyrite accompanied with 24% arsenopyrite.

Mar 2, 2022

By M. A. Berdine, C. N. Thompson, D. Brock

The raise bore method of shaft construction has been success-fully used in the mining and construction industries for over thirty years. In the mid 1990’s, Twentymile Coal Company (“TCC”), now affiliated with RAG American Coal Company, used this method for a moderately deep small diameter shaft and the raise bore and slash method for a shallow larger diameter shaft. In late 2001, TCC contracted to raise bore a 431-meter deep, 6.2-meter diameter shaft. During the raise bore and shaft lining processes, regional horizontal stress fields resulted in extensive elliptical caving beyond the original design diameter. This paper discusses the engineering approaches and procedures used to safely complete construction of the raise bore shaft.

Jan 1, 2004

By S. C. Suboleski

In a high risk venture such as mining where capital is committed and contracts are signed on the minimum of information, decisions are based primarily on production forecasts derived through consideration of such factors as management-labor relations, mining practice, variations in physical conditions and the equipment applied. Among these factors, the physical conditions offer the least opportunity for control and, due to the wide range of mining conditions that may be experienced, little effort has been made to develop objective methods for measuring their effects on mine out- put. The aim of this paper is to demonstrate a method for assessing these relationships that can be applied under a wide range of conditions both in new mines and in working sections where there is a need to determine the impact of proposed operational modifications. psing empirical data from active underground mines, a mathematical model was developed to derive a set of regression equations for predicting production as a function of mining conditions

Jan 1, 1980

By K. Burke, K. L. Myers, R. Espell

Barrick's Goldstrike AA heap leach pad is an HDPE-lined facility that was used for gold recovery from low-grade ores using conventional cyanide heap-leach technology. The pad was operated from 1987 through 1999. Goldstrike prepared a unique reclamation plan for the AA leach pad facility to provide for a cost-effective, environmentally sound facility closure and to fulfill the State of Nevada's closure requirements. The traditional Nevada leach pad closure procedure involves rinsing to reduce the cyanide concentration to an acceptable level followed by reclamation. However, rinsing does not typically reduce certain metals and compounds, and some constituents may increase in concentration with rinsing. A closure scenario to effect limited infiltration through installation of a capillary cover for the leach pad was developed. The capillary cover was constructed by placing a fine-grained layer above the coarse-grained spent leach material to create a capillary break. In an arid climate such as in Nevada, the fine-grained layer will rarely reach saturation, and the cover will be able to store water during precipitation events and will allow removal of water through evaporation and transpiration (ET) during the growing season. A 1.22-m (4 ft) cover thickness was selected as the optimum design cover thickness. The drainage network on the surface of the recontoured AA heap leach pad was specifically designed to enhance the re vegetation, reclamation and sediment yield control aspects of the AA heap leach pad closure, while resulting in a natural looking surface that is compatible with the surrounding topography. Adjacent natural topographic features were used to establish target design parameters for recontouring and erosion-control design.

Jan 1, 2002