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By P. M. May, V. Gella

The deportment and speciation of trace elements during mining and minerals processing is becoming an area of increasing concern with regards to potential health and environment risks. The use of chemical modelling can enhance our basic understanding of the deportment and speciation of trace metals under conditions present in gold processing solutions, and assist in laboratory and field investigations. In this paper, we report the results of chemical speciation modelling using the JESS software package for the trace toxic elements Pb, Cd, Hg, Se and Te in cyanidation solutions of varying salinity and relate the models to experimental data. The speciation of mercury is examined in detail.

Jan 1, 2011

By Irving Hauser

The determination of new ways to cut costs in then times of economic uncertainty is essential in running a successful business. Arco Petroleum Products Company a Division of Atlantic Richfield Company recognized an opportunity for a substantial cast savings in transporting calcined petroleum coke to market by simply building an economical port facility at a location that would enable them to drastically cut their normal rail haulage distance.

Jan 1, 1982

By Luis Bergh, Iván Rojas, Juan Yianatos, Luis Vinnett

"At present, flotation rate characterization follows standard measurements to identify the overall flotation performance looking at the feed, tailings and concentrate in flotation cells or banks. This classical approach does not take into account the evolution of the true collection rate down the flotation banks explicitly. The potential for identifying the impact of the mineral characteristics (size and liberation) as well as the effect of different manipulated variables (reagents, froth depth, gas dispersion) on the true flotation process remains hindered. Top-of-froth (TOF) measurements, which consist of sampling the first layer on the froth surface, have been used to characterize the mineral collected by true flotation in rougher banks. The information provided by TOF samples allows evaluating the floatable mineral evolution (grade, particle size, liberation) down the bank. In this work, an indirect approach to estimate the flotation rate along rougher flotation banks is proposed. The new approach is based on the decreasing of collected mineral grades (on top of froth) and the feed characteristics. Flotation rates per liberation classes were used to reconstruct the TOF grades from the feed information. This approach requires a simple froth surface sampling, without constraints typically observed during mass balance surveys and uncertainties on the mineral recovery estimation. The proposed methodology was successfully applied at industrial scale using TOF measurements together with QEMSCAN information."

Jan 1, 2014

By Charles T. Holland

The tonnage produced on mechanized automated retreating longwall faces in the United States is growing rapidly. This time last year some 14 faces were operating, and in addition to that, three were known to be down looking towards revision or repairs before being placed back in service. These, it is believed, are now in service. It is estimated at the present time, therefore, that somewhere between 20 and 25 faces are being operated in the country. A survey made last year by the School of Mines, West Virginia University, indicated that longwall mining in general has been beset with a great many problems, some more serious than others. The problems that we propose to discuss here are those pertaining to roof and floor trouble in the tailgates. Longwalls are operating in this country at the present time under an overburden ranging from 200 feet to nearly 3000 feet. Main and tailgate entries are operating in panels of up to five each, with the width of the pillars between these entries varying from 20 to 50 feet. Face lengths are running from 270 feet to 670; actually a face 800 feet long should be possible. The most economical face is often spoken of as being around 450 feet.

Jan 1, 1969

By Waleska Campos Guaglianoni

With the growth of nanoscience and nanotechnology, the synthesis of nanostructured oxides has received a special attention. Metal oxides are widely used in the manufacture of microelectronic circuits, piezoelectric devices, fuel cells, catalysts, filters and bactericides systems. These metal oxides represent a large class of semiconductor materials suitable for photocatalytic processes. In recent years, new materials of this class such as TiO2 and ZnO have been developed due to their photo-catalytic abilities to degrade various environmental pollutants. This work aimed to evaluate the photocatalytic activity of zinc oxide previously synthesized by combustion synthesis in solution using citric acid as fuel and different reasons fuel/oxidant. After synthesis, the powders were subjected to heat treatments at different temperatures and photo-catalysis. The photocatalytic activity was evaluated by the degradation of a solution of methyl orange in a photochemical reactor of UV illumination, after which the transmittance of the samples measured with the assistance of a spectrophotometer. To analyze the results, a commercial zinc oxide was used as standard. The products of combustion synthesis in solution showed that photocatalytic activity varied according to the ratio fuel/oxidant and as a function of heat treatment. The results showed a higher photocatalytic activity for the products obtained with disabilities fuel in the reaction and heat treated.

Aug 8, 2018

By R. A. Bilonick

Sampling is used in all scientific, engineering, marketing, and financial disciplines. The scientific theory of probabilistic sampling is a well established field, providing a general framework for basic methods that can be applied in fields that would appear to have little in common. The revolution in sampling occurred, in part, as a response to the need for quality control in industry during the Second World War. Since this time probabilistic sampling methods have been replacing pre-scientific non-probabilistic methods of sampling. This has not been the case, however, in the mineral industries in the United States. No general agreement on a theory applicable to all sorts of particulate materials has been reached. As a result, non-probabilistic methods are still widely used and the measurement of sampling precision - the hallmark of scientific sampling - is unknown. Much of the research on particulate material sampling that has been carried out over the last 40 years can be characterized by a lack of theoretical reasoning and rigor, an unwillingness to acknowledge previous work, and a lack of integration with existing, established scientific sampling theory. Non-standard statistical terminology is used and often standard statistical terms are misused. The confusion that has resulted is reflected in ASTM and IS0 sampling standards and in the practice of particulate material sampling.

Jan 1, 1986

By S Ferguson, G Noble

The mining industry is facing economic pressures to treat more challenging and lower grade ore types, as well as pressure relating to environmental impact and social license to operate. Preconcentration through bulk ore sorting has the potential to benefit all these areas by enabling mining operations to divert material of low economic value prior to processing, thereby achieving higher feed grades and recovery, while reducing the processing plant and tailings dam footprint and capital required throughout the life of mine. The effectiveness of bulk ore sorting depends on the heterogeneity of material at the measurement location, as well as the accuracy and precision of the measurement. An understanding of ore heterogeneity can be assessed using drill core data, which provides metre by metre elemental assays. This paper reviews such data and assesses the grade distributions over different scales, which suggests that sufficient heterogeneity exists at mining scales to allow the potential for bulk ore sorting. Prompt Gamma Neutron Activation Analysis (PGNAA) technology has proven to be a successful measurement technique within many industries, including mining. PGNAA was first developed in the early 1980’s for the measurement of the elemental composition of bulk materials on a conveyor belt. Today, Pulsed Fast Thermal Neutron Activation (PFTNA) technology is also applied in elemental analysis of bulk materials and has some advantages for bulk ore sorting. In order to enable effective bulk ore sorting, however, a PGNAA/PFTNA analyser must be designed to provide a representative bulk ore analysis with the necessary accuracy and precision. Examples are presented to provide an understanding of the factors affecting PGNAA/PFTNA performance in relation to effective bulk ore sorting.

Nov 10, 2020

By R. A. Beall

As part of an ongoing program to develop high-quality materials with improved performance and service lives, and to conserve critical minerals, Bureau of Mines, U.S. Department of the Interior, researchers studied the process of hot-rolling metals, alloys, and composites in vacuum. First, a comprehensive review of the literature is presented, including the advantages and disadvantages of using vacuum. Next, details of hot-rolling titanium, chromium, and molybdenum-iron bimetal are given. Finally, the design of new equipment is described. At this time, it is uncertain whether hot-rolling metals in vacuum will gain commercial acceptance in the future.

Jan 1, 1979

Geological discontinues in the coalbed, such as faults, sandstone channels, permeability facies, lithotype changes, and large scale partings in the coal seam, can cause intermittent production problems or produce unexpected amounts of water or gas from degasification boreholes. These discontinuities not only can impact methane emissions into the mine workings, especially if they hinder proper and effective degasification of the coalbed but may act as conduits for methane flow from gassy strata into advancing mine workings. The effects of these discontinuities are still under debate by mining and gas production experts. This study presents a numerical investigation using reservoir simulations of the effects of partings and permeability facies and lithotype changes on the production performances of vertical and horizontal degasification boreholes, as well as the emissions during longwall operations. In this work, the grid block was designed in a multi-layer 3-D structure which enabled spatial descriptions of the geometries and properties of the discontinuities within the coal seam. The studied coal seam discontinuities and their properties were distributed arbitrarily within the model. Production was simulated by vertical and horizontal boreholes. Degasification boreholes operated two years prior to start of the mining. The results of this numerical study show that in coal seams with major heterogeneities and discontinuties, the geometry and location of the boreholes are important for improved gas production. These considerations are also important for controlling methane and water inflow into the working environment during longwall mining.

Jan 1, 2008

"HPGRs operate in a wide array of applications in mining and minerals. These range from relatively coarse crushing of copper and gold ores at one end of the spectrum to the processing of fine iron ore pellet feed and fine industrial mineral products at the other. Traditionally these circuits involve the treatment of relatively moist materials in pre-grinding circuits; using single stage HPGRs in open circuit or as a closed circuit operation with screening or partial product recycle. More recently, HPGR is increasingly deployed in dry grinding in combination with air classification. The high throughput demonstrated by larger HPGRs has stretched the application towards coarser size reduction duties for a number of new projects. At the same time, the basic principle of inter-particle crushing for generating a product with a high fines proportion gives ground to investigate applying the technology further towards finished product duties. The advantages that HPGR brings are clear. Multi Stage grinding enables energy efficient size reduction across more of the comminution circuit. Primary HPGR serves for a coarse grinding duty, whereas a secondary HPGR is geared towards generating a fine product for downstream processing or even a finished product. This publication summarizes some of the features of staged HPGR circuits and discusses some examples of operating and projected applications.INTRODUCTION In most HPGR applications, the grinding units are used as a single process stage, either in open circuit, such as for pebble crushing [Rose 2002, Westermeyer 2000, Van der Meer 2015] or in closed circuit with classification [Van der Meer 2009, 2012] or product recycling [Van der Meer 2010]. Where a higher plant capacity is required, the HPGRs are commonly installed in multiple lines in a parallel arrangement [Parker 2005, Koski 201, Vanderbeek 2006]. HPGRs can take a wide range of feed size distributions, and grind this down to a product with a high fines content. In general view, there is a limit on the size reduction range that even an HPGR can provide. Grinding down from a very coarse ore (e.g. 70-100 mm) to a very fine product (e.g. 100 microns range) is stretching the ability of a single stage HPGR circuit. Fine grinding generally requires a classification stage that returns the classifier oversize to the head of the HPGR circuit. From one point of view, it can be demonstrated that when recycling a large proportion of fines and middlings back to the HPGR feed results in an effective feed with an overrepresentation of middlings and fines, which will eventually reduce the grinding efficiency and consequently result in an increased recirculation mass flow [Van der Meer 2014]. From another point of view the large recycling mass puts a strain or even a limit on the capacity of present-day conveyor capacity."

Jan 1, 2018

By Jr. Driscoll

The thermoelectric properties of yttrium monoarsenide, yttrium monoanti-monide) and ternary materials from the Y-As-Se and Y-Sb-Te systems were investigated by the Bureau of Mines from room temperature to 1,000° C. The maximum calculated figure of merit for yttrium monoarsenide and yttrium monoantimonide was 2 x 10-5 ° C-1. YAs and YSb were semimetallic conductors with low Seebeck coefficients and electrical resistivities. The values of the Seebeck coefficient and electrical resistivity of the Y-As-Se and Y-Sb-Te materials were between those of the yttrium selenides and tellurides and of YAs and YSb, respectively. The maximum power factor calculated for the Y-As-Se materials was 2 X 10-5 watt/cm ° C2 which yielded an estimated figure of merit of 6 X 10-4 0 C-1. Most of the Y-As-Se compounds had high Seebeck coefficients and moderately low electrical resistivities. The Y-Sb-Te materials were degenerate semiconductors with power factors of 6 X 10-8 watt/cm ° C2.

Jan 1, 1967

By S. Yerel

Block cutter machines have been extensively used in natural stone industry, which is a sub-section of mining industry. In this study, the costs occurring in plate losses cut from Bilecik beige marble with a circular saw block cutter machine have been predicted using Statistical Process Control (SPC) techniques. One of SPC techniques is Shewhart control charts such as mean control chart. These charts have been efficiently at determining the plate losses. The costs occurring in plate losses have been calculated by using the result of Shewhart control chart. Finally, this study presents the necessity and usefulness of SPC techniques in assessment of natural stone industry.

Jan 1, 2010

By Sengstock G. W, Spathis A. T

Benchmarks of mine equipment involved in the excavation process of coal mines would suggest that such equipment is not always operating at an optimum level. Dragline operations and truck/shovel operations rely on efficient use of their plant in order to maintain high mine throughput. The first process which affects the material to be excavated is the drilling and blasting process. Drilling and blasting delivers a fragmented material with a given disposition ready for excavation by mine equipment. As mine operators demand more productivity from their major excavating equipment, many sites are considering the use of productivity monitors to measure their outputs. Some of these productivity improvements will be directly related to the drilling and blasting process, so that as the monitoring systems improve, the opportunities to evaluate all drilling and blasting variables will also improve. This paper reviews current and newer methods for monitoring equipment productivity in mines. These include simple time and motion studies obtained by either manual timing of processes or by automated data collection equipment being adopted by the industry. Case studies for truck/shovel operations are discussed and the productivity improvements are compared with typical industry standards. These improvements relate specifically to parts of the load, haul and dump cycle and the potential for significant improvements are identified. Particular opportunities for drilling and blasting improvements are also presented.

Jan 1, 1995

By J. M. Riley

A fluorometric method using morin in an alkaline-buffered chelating solution has been developed by the Bureau of Mines for determining beryllium in ores and mill products. Apparatus for measuring fluorescence intensities of the beryllium-morin reaction is described. Preparation of the sample for analysis consists essentially of digestion with sulfuric, nitric, and hydrofluoric acids, fusion of the residue with sodium carbonate and sodium borate, Solution of the melt with sulfuric acid, and proper dilution. Chemical separation of other ions is usually unnecessary. The method rave reliable beryllium determinations on samples in the 0.01- to 0.37-percent BeO range. The method is particularly applicable to low-grade beryllium ores; however, semiquantitative beryllium determinations have been made on beryl containing 12.0 percent BeO.

Jan 1, 1956

By D. Harrington

Although the explosion-fatality record for the fiscal year 1944 showed considerable improvement over those of the preceding 4 years, it is still fur from creditable, and the coal-mining industry and agencies interested in the prevention of coal-mine accidents should not be satisfied until accidents from explosions and fires are eliminated. In view of present knowledge of the methods of preventing explosions and fires, such disasters are inexcusable and discredit the mining industry. Despite this knowledge, far too many coal¬mine operators and employees continue to follow procedures that have resulted in disasters in the past. Included in the appendix to this circular are a number of safety measures designed to prevent coal-mine explosions and fires and metal-mine fires. Their adoption is essential if explosions and fires are to be prevented, as certainly they should be. An epidemic of disastrous mine fires of electrical origin during the past 2 years emphasizes the need for better methods of protection of underground electrical circuits. At present, committees of mining-electrical engineers, electrical-equipment manufacturers' representatives, and others are cooperating with the Bureau of Mines seeking means to solve this problem.

Jan 1, 1945

By Beaumier. M., J. -P. Lalonde

"Les réultats obtenus dans les sols sur quatorze aires d'essai et six cheminements régionaux dans I'A bitibi-Témiscamingue indiquent clairement qu'il existe des variations régionales importantes dans les teneurs en éléments traces de l'horizon A1 formé sur l’épais recouvrement glacio-lacustre de cette région. Les anomalies obtenues correspondent à celles qui ont été décelées lors de précédents levés des eaux souterraines et du till de base.Selon les critères d'évaluation utilisés, treize des quatorze aires d'essai ressortent comme anomales dans Ie contexte abitibien; dix de celles-ci sont tres anomales. Ceci suggère fortement qu'un levé régional de sols, fondé sur une approche multi-éléments, identifierait entre 70 et 90 % des cibles géochimiques reconnues par des échantillonnages en profondeur. Les résultats d'un échantillonnage systématique effectué sur une région de 1000km2 viennent aussi appuyer cette hypothèse. Conséquemment, les sols formes sur les sédiments glacio-lacustres sont un médium très utile pour inventorier de grandes regions recouvertes par ce typ e de sédiments.L 'horizon A1 est Ie plus utile pour ce type de levé parce qu'i1 est facil e d échantillonner, qu 'it assure une plus grande constance du typ e de matériel échantillonne et qu'il contient des teneurs accrues.De multiples mécanismes de dispersion géochimique ont joué des rôles d 'importance variable pendant et après la mise en place des sédiments glacio-Iacustres. Les plus importants sont la pression hydrostatique, la diffusion chimique et électrochimique ainsi que la bio-accumulation. Si on veut progresser dans la connaissance de ce milieu complexe, on devra adopter une approche plus systemique tenant compte de I'interaction des mécanismes agissant dans l'environnement global avant, durant et apres Ie depôt du mort-terrain."

Jan 1, 1984

By H. Sarvamangala

Selective separation of alumina, silica, calcite and apatite from hematite was achieved through microbiologically induced flotation and flocculation in presence of bacteria (B.subtilis) and that of hematite from apatite after interaction with yeast (Saccharomyces cerevisiae). Bacterial and yeast metabolites containing extracellular proteins were characterized from mineral-grown cell free extract. Bacteria and yeast can adhere to mineral surfaces and influence subsequent separation of the minerals. Bacteria functioned as a stronger depressant for hematite, while yeast cells depressed apatite at neutral pH. Selective affinity of the bacterial and yeast cells towards the mineral surface was observed through adsorption studies. Extracellular proteins (EP) were isolated from B.subtilis and yeast. The protein profile of the EP of bacterial and yeast cells grown in presence and absence of minerals was studied. This study has demonstrated the utility and amenability of microbially-induced mineral beneficiation of iron ores through bacterial and yeast cells and their metabolic by products.

Sep 1, 2012

By K. A. SPENCER

THE production of soft coal from strip mines in the United States has shown a remarkable growth in the last sixteen years, increasing from one and one-quarter million tons in 1914 to approximately twenty-two million tons in 1929. This is a growth of approximately 1660 p& cent, as compared with a growth of approximately 20 per cent in the underground mines for the same period. But even with this marked in- crease the total tonnage produced by open-face mining represents only 4 per cent of the nation's soft coal tonnage.

Jan 1, 1931

By Fred C. Delabbio

The successful implementation of a new technology in an underground production mine requires many challenges to be overcome. These challenges include mine hardening of new technology, mitigation of safety risks and hazards, mine operation support, and technology transfer to mine staff. In the end, the majority of these challenges relate to the human aspects of implementation. The approach selected to overcome these challenges must be customized and appropriate for each unique situation. This paper outlines the approach used to address these challenges as part of successful implementation and resulting demonstration of the hydrogen fuel cell locomotive at the Placer Dome (CLA) Limited, Campbell Mine. This technology demonstration at Campbell Mine is critical for determining technical, regulatory and implementation aspects to be incorporated into future fuel cell prototypes such as the LHD project.

May 1, 2003

By Owen Matthews

Introduction For the past year and a half, the mill of Cochenour Willans Gold Mines, Limited, McKenzie Island, Ontario has been roasting arsenopyrite-gold concentrates, prior to cyanidation, by means of a roaster employing techniques that are new and novel. The roaster is known as the Dorrco 'fluo-solids reactor', and the technique as 'fluidization'. The reactor has demonstrated its ability to roast a flotation concentrate containing arsenopyrite, pyrite, stibnite, small quantities of other sulphides, and some lime silicates and carbonates, yielding a calcine consisting mainly of porous iron oxide, plus the gold values. This calcine is readily amenable to cyanidation. Bulk shipments of concentrates to a distant custom smelter, as practised prior to this installation, has thus been eliminated, with appreciable savings in smelting charges, freight costs, and interest losses during shipment and smelting. This is the pioneer installation of fluo-solids roasting at a Canadian mill and up to the present performance results have not been published. It is the purpose of this paper to present the information now available for the benefit of other millmen who may be confronted with identical or similar problems to those encountered and solved at Cochenour Willans.

Jan 1, 1949