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By G. T. Lineberry

Horsepower requirement is recognized as a most important equipment characteristic. Other critical equipment characteristics will be isolated and analyzed by traditional operations research techniques, using off-highway trucks as an archetype. A computer search technique has been developed, employing various production and cost analyses. With this model, the optimum combination of horsepower, capacity, and velocity can be found, minimizing handling cost per ton. An example of the program's use and interpretation of its results will conclude the paper.

Jan 1, 1984

By Turan Uysal, Ramazan Aydogmus, MURAT ERDEMOGLU

The paper investigates the effects of calcination for thermal activation and intensive milling for mechanical activation on aluminum recovery by acid leaching of pyrophyllite ore enriched via attrition scrubbing and froth flotation. The study compares these methods in terms of energy consumption and aluminum recovery, concluding that mechanical activation is more economical and environmentally friendly.

Nov 1, 2023

By Jieliang Wang, Shiwen Yi, Zhao Cao, Peng Zu

Bayan Obo ore contains mainly bastnaesite, monazite and associated iron, fluorite, calcite, dolomite, barite, and trace amount of columbite. Due to its complex mineral compositions and similar mineral properties, it is difficult to separate and obtain rare earth and fluorite concentrates with high purity by conventional magnetic separation and flotation. In this paper, a stepwise magnetic separation process comprised of wet permanent magnetic separation (PMS), wet electromagnetic separation (EMS), and superconducting magnetic separation (SCMS) was proposed to pre-concentrate iron, rare earth, and fluorite minerals from Bayan Obo ore. The results showed that iron, rare earth, and fluorite preconcentrates with high purity and low impurity content could be achieved, which might be helpful to shorten the technological process and improve the separation efficiency for the subsequent flotation of iron, rare earth, and fluorite minerals.

Sep 15, 2020

By BHAMIDIPATI S. SASTRY, SRIVATSAN J. SRIDHARAN

Pressure losses in mine ventilation systems are estimated using friction factors and shock loss factors. The efficient planning and designing ofmine ventilation systems depend on the accuracy of the friction factors as well as the shock loss factors that are taken into consideration. While there is a much more acceptable knowledge of what constitutes friction loss in mine roadways, the shock loss factors are in general readily not available for all possible contexts of flow separation phenomena in mines. One such special case of shock loss in mines is the train of mine cars in the airway. Mine cars are widely used for the transportation of material, and the information on shock loss factor for mine cars is limited. This paper examines the pressure loss occurring due to a train of mine cars in an airway using scale model studies and numerical investigations. Computational fluid dynamic (CFD) studies are conducted using four different turbulence models. The performance of different turbulence models is analyzed by comparing it with the experimental results. The study suggests that the boundary layer resolution method is significant in the simulation of shock loss. From the study, it is found that the shock loss factors from presently available model overestimate the pressure loss by 7 to 15 times. A better prediction model for the shock loss factor of a train of mine cars in the airway is proposed using the experimental results.

Jul 24, 2020

By J. F. Oyler

One of the most important applications of material handling engineering technology occurs in iron ore pelletizing plants. Although the total installed value of material handling systems in such plants, as well as in many other modern process plants, is a relatively small percentage of the value of the plants (5 to 10% perhaps), their significance is considerable. Indeed this significance equals that of the more expensive process equipment in the plant, since the failure of any component of any system causes, shutdown of the entire plant. It is because of this increased consequence of failure that design criteria for process plants are more conservative than for conventional material handling applications. A second unique characteristic of material handling technology applied to process plants in general is the variety of materials being handled and the wide range of problems this variety presents. One extreme encountered is the stickiness of filter cake. Here the entire design effort is aimed at keeping the material flowing through transfer points and preventing it from building up on components. Another extreme is the conveying of fired pellets - hard spheres with a very flat angle of repose and abrasive characteristics severe enough to make conventional wear plate materials impractical.

Jan 1, 1976

By M. P. Miano

Matching the productivity gains of continuous mining machines with the ever increasing performance levels achieved by longwall units has required creative thinking to assure that development is completed in time for uninterrupted longwall production. By using management information systems to coordinate support operations, the most productive planning decisions can be made. This paper focuses on the role of computer technology tools in achieving improved productivity from both longwall and continuous miner sections. The primary emphasis is on the planning process and the methodology developed to guarantee the best allocation of management and manpower resources.

Jan 1, 1993

By Gary English

"Tunnel safety is evolving as science, engineering and technology make advances. Applicable safety codes and standards simply do not cover all the potentials of design, construction and operation. This paper reviews a series of tunnel projects code gaps in Seattle USA that were uncovered during the design and construction of a new highway tunnel, conversion of bus tunnels to combined road and rail tunnels, new rail tunnels using TBM and NATM, conversion of a road tunnel to light rail, and retrofit of an existing road tunnel to add lanes and improve safety systems. The perspectives of the ‘fire code official’ (Authority Having Jurisdiction) on methods to identify and resolve gaps in safety code and standard regulations, while garnering the consensus of the owner, designer, and contractors are presented. Additionally, the emergency responder command perspective on safe tunnel design, tunnel rescue during construction and operational safety is explained TUNNEL SAFETY EVOLUTION The underground has become nearly the only option to provide essential transportation corridors to continue our economic growth in key global areas. Tunnels are not built on a whim. Often significant portion of a regions wealth are invested to meet current, and hopefully future transportation demands. There are more transportation tunnels being built now than at any time in the planets history. The location of these tunnels is often selected for us based upon regional demand. Most commonly under densely populated urban centers and between populations’ centers to bypass geologic conditions like mountains and water bodies. Tunnels are being built in unforgiving soils, between tectonic plates, in extremes environmental conditions and often, under the very heart of the highest density population centers on the planet. All of these locations can bring with it conditions that challenge our common assumptions about safety. These extraordinary locations and soils create risks for both those constructing the tunnel, and in design engineering to meet the ‘minimum’ requirements at the lowest costs. There is lengthy history of above ground safety. Most countries and major local jurisdictions have adopted, or created safety requirements for the construction of above ground buildings. Through decades of use, these safety requirements have evolved, changed and been expanded to cover a wide gamut of actual and potential safety risks. However, the use of the underground for tunnel transportation corridors has grown exponentially with limited attention to safety requirements."

Jan 1, 2016

By Bruce D. Hebb, Shahin Shadlou

Fiber Reinforced Polymer (FRP) is an excellent material choice for a broad spectrum of corrosive fluids and, in many cases, offers the best value per dollar. FRP Flanges present the greatest design challenge of all standard piping components. The theory underlying the design of flanges is very complex. In addition, due to the nature of FRP material, proper fabrication of the flanges is as critical as the design. In this review, the challenges of making FRP flanges along with the design techniques and best practices of fabrication that will lead to a high-quality flange will be discussed.

Feb 1, 2024

By Ehsan Moosavi, Kamyar Tolouei

In open-pit mines, the long-term production scheduling optimization problem (LTPSOP) is a complicated problem that contains constraints, large datasets and uncertainties. Due to its dimensions and NP-hard nature, it is usually difficult to find an ideal solution to the LTPSOP. The optimal schedule generally restricts the ore, metal and waste tonnages, average grades, and cash flows of each period. In this paper, to synthesize grade uncertainty into the strategic schedule, a stochastic integer programming (SIP) framework is presented to LTPSOP. The objective function of the SIP model is to maximize the net present value and minimize the risk of deviation from the production targets considering grade uncertainty simultaneously while satisfying all technical constraints and operational requirements. Instead of applying one estimated orebody model as input to optimize the production schedule, a set of equally probable orebody realizations is applied to synthesize grade uncertainty in the strategic schedule and produce a more profitable and riskbased production schedule. To solve the LTPSOP, the hybrid approach with the augmented Lagrangian relaxation method, the Harris Hawks optimization, the Random Forest method and Monte Carlo method was proposed. To indicate the applicability of the model, a case study on a gold mine was implemented. The framework displays the capability to minimize risk and improvement in the expected net present value and financial profitability .

Jun 25, 2023

By R. W. Chadwick

Coal was discovered in South Africa in the mid 1830's. The earliest exploitation of modern times was probably in Natal where, in a letter dated 20 August 1842, a Captain Smith mentions that a wagonload of coal brought to Pietermaritzburg, was sold. Until the discovery of diamonds in 1867 and the Witwatersrand gold in 1886, coal mining satisfied a very small domestic demand. By 1889, at least four collieries were operating in the Middelburg-Witbank district, some 120 kilometres East of Johannesburg, and mining had star- ted at Vereeniging, about 50 kilometres to the South of Johannesburg. A map of South Africa is shown in Figure 1 and an enlargement of the main coal mining areas in Figure 2.

Jan 1, 1982

By P. K. Parhi

The extraction of nickel has been carried out by the hollow fiber membrane technique using D2EHPA as the mobile carrier from the manganese nodule leach liquor after separation of Cu(II), Zn(II) and Co(II). The experiments were designed according to central composite design (CCD), which is a response surface methodology. The process parameters used for the experimental design were: pH, concentration of D2EHPA in the membrane phase, flow rate and H2SO4 concentration in the strip solution. Based on the analysis of variance, a reduced quadratic model was found to best fit the experimental data. The process parameters were optimized to maximize the nickel flux and the optimized conditions were flow rate: 630 mL/min; pH: 6.37; D2EHPA: 1.15 mol/L (1,150 mol/m3) and H2SO4: 2.39% (430.2 mol/m3), for a maximum nickel flux of 7.08 x 10-5 mol/m2.s, which was in good agreement with the actual Ni flux of 6.99 x 10-5 mol/m2.s.

By Gordon C. ‘Bud’ Presley

The pumice and pumicite review arrived too late for the June issue. Estimated domestic production of pumice and pumicite in 1992 was up compared with 1991, according to US Bureau of Mines statistics. The Bureau estimate of domestic production of 400 kt (440,000 st) for 1991 turned out to be 401 kt (442,000 st) of actual production, the lowest since 1989. In 1992, the estimated the value of pumice and pumicite sold or used in the United States was $11.6 million, up only $200,000 from the 1991 value. There was an increase in the mine, or mill, average price from the five-year low of $11.44/t ($10.37/st) in 1986 to $26.42/t ($23.96/st) in 1992. Estimated tonnage produced in 1992 was 439 kt (484,000 st). Apparent domestic consumption was 642 kt (707,000 st), up 135 kt (149,000 st) from 1991. Imports for consumption were estimated to be 215 kt (237,000 st) last year. Domestic production supplied 68% of the demand in 1992, with net imports supplying the remaining 32%. This compares with domestic production sup¬plying 53% and net imports supplying 47% of the apparent consumption in 1988. Exports were about 900 t/a (1000 stpy) for the period 1984 to 1988. In 1989, exports rose sevenfold to 7 kt (7700 st) and to 20 kt (22,000 st) in 1990. The Bureau of Mines reported that the amount of pumice and pumicite exported in 1992 was 12 kt (13,200 st). It is assumed that these exports were from the Pacific Coast because imports, mainly from Greece, continued to be a market factor on the East Coast and the Gulf Coast States in the United States.

Jan 1, 1993

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

Water and wind erosion of toxic zinc and lead smelter waste is one of the most urgent environmental problems to be solved in the Silesia region of Poland. Over 87 x 106 Mg of various mining wastes were disposed of in uncontrolled piles leading to soil, water, and air pollution in highly populated areas. Welz and Doerschel process Pb/Zn smelter wastes were stabilized in the summer of 1994 by application of heavy loads of CaCO3 (30 Mg/ha), CaO (1.5 -15 Mg/ha), and municipal biosolids (150 -300 Mg/ha), followed by seeding with a mixture of acid-and salt-tolerant grass species selected in a pot experiment. Vegetation was successfully established on 85% of the Welz material demonstration plot area (0.5 ha), even though it was initially high in water-soluble Zn, Pb, and Cd ranging from 0.4 to 1311,0.1 to 5.8, and 0.05 to 55 mg/kg, respectively. Standing biomass averaged 3.3 Mg/ha on the stabilized Welz waste zone by the end of the third growing season (1997). The revegetation of much of the Doerschel material area failed initially because of extremely high salinity (16 dS m-1), high content of water soluble metals (Cd in particular), and heavy compaction. The area was capped (15 cm) with waste lime and retreated with bio-solids (300 Mg/ha) in 1995, and standing biomass averaged 2.9 Mg/ha in the fall of 1997. The observed plant response to bio-solids and lime indicates this approach to be an environmentally beneficial technology as compared to the traditional methods utilizing topsoil covers.

Jan 1, 1999

By X. P. Zheng

Barium fluorphlogopites were synthesized in the laboratory in order to investigate the effects of composition and crystal parameters on surface properties and floatability. The negative surface charge of mica is determined by the barium content, the crystal cell volume, the distance between layer structure and the Ba-O bond length. The higher barium content, the larger the cell volume and distance between the layer structure and the longer the Ba-O bond, the more negatively charged the surface is and hence the more easily adsorbed to cationic collectors. When an anionic collector (sodium oleate) is used, barium oleate forms on the mica surface and hence chemical adsorption occurs.

Jan 1, 1993

By Erik Klohn

The El Soldado copper deposit occurs in volcanic rocks of alkaline affinity of Lower Cretaceous age. The orebodies are discordant and show strong structural and lithological control. The mineralizing event was accompanied by hydro- thermal alteration expressed as carbonatization, silicification, and chloritization. Individual orebodies contain bornite-chalcopyrite cores which are surrounded by haloes dominated by chalcopyrite and pyrite respectively. The sulfur isotope composition of copper sulfides strongly suggests the sulfur is of magmatic origin. Fluid inclusion studies show the mineralizing fluid to be a highly saline NaC1-CaC12, brine. No evidence of boiling was found. The deposit is most likely of epigenetic origin. Hydrothermal fluids were produced during crystallization of a sodium rich trachytic magma during the waning stages of an episode of alkaline magmatic activity. Similar copper deposits along the Chilean Coastal Range may also be associated with alkaline host rocks.

Jan 1, 1986

By Duane L. Abata

This paper discusses recent technology dealing with the use of computer graphics in the mining industry and presents a newly developed computer software package specifically designed for use in underground mining operations. This software package, developed under a United States Bureau of Mines contract, 1) displays mine ventilation schematics and other representative illustrations for a real time data acquisition system and 2) utilizes the Bureau-owned Minefire and Ventilation Code for display of ventilation and contamination predictions on the microprocessor system. The package utilizes a unique system of display indexing that provides a simple yet efficient method of recalling a series of mine schematics detailing an underground operation and an alarm acknowledgement scheme that provides an effective method of identifying problem areas which may exist in the mine network. The package was written in Fortran for a 64 kilobyte, Z80-based microprocessor-computer.

Jan 1, 1984

By Chunbao Sun, Qi Liu, Chao Wang

Entrainment is a process by which fine and ultrafine particles are transferred to the flotation froth from the top of the flotation pulp, and eventually discharge to the concentrate product, evenwhen they are not attached to gas bubbles. Therefore, entrainment can be considered as a two-step process, one at the upper layer of the pulp to the flotation froth, and the other from froth to the concentrate. Entrainment is inevitable for both hydrophobic and hydrophilic minerals and is one of the significant factors affecting concentrate grade. This paper provides a comprehensive review of the entrainment mechanisms and entrainment models, as well as a summary of the main factors affecting entrainment and the techniques thatmay be used to lower or eliminate entrainment. Based on the review, we point out that selective aggregation of fine and ultrafine gangue minerals using appropriate process aids (polymeric depressants, inorganic salts, etc.) to increase their particle sizes appears to be a convenient and economical method. Directions of further research along this line are discussed.

Aug 31, 2020

By A. Lashgari

Surface coal mining in the Appalachian region consumes a significant amount of energy in the form of diesel fuel and blasting agents. emission of oxides of nitrogen (Nox) from these sources represents an environmental challenge to the mining industry. this paper presents the results of research work related to determination of Nox emission of mining equipment and blasting agents, which is part of a broader industrial project conducted by the Appalachian research Initiative for environmental research (ArIeS). Data for this project are collected from an operating surface coal mine in West Virginia. the research work presented here may be used by mining professionals to aid in quantifying Nox emission and determine strategies for reducing its overall environmental impact.

Oct 1, 2013

By J. H. Kelley

In this paper, we show that the methane emission and the dust generation in under-ground mining currently and in the future pose operational, health and safety conditions which adversely Impact face productivity and worker satisfaction. One solution is the use of a dual-aircourse system of ventilation. In this concept, one aircourse captures and exhausts to the surface the dust generated and the methane emitted in coal/mineral fragmentation while a second aircourse provides workers with cleaner air for breathing and comfort. Various dual-aircourse configurations adapted to the Variable Wall Miner are analyzed and compared with conventional mining in gassy seams, indicating a marked reduction in the required air quantity and the number of aircourses.

Jan 1, 1996