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By J. A. Lamonica

The Bureau of Mines studied a pulsation damping device designed to smooth pulsating flow in personal respirable dust samplers. The effect on the pulsation dampener efficiency of six parameters was investigated, as follows: Volume, diaphragm elasticity, diaphragm area, center orifice area, inlet-outlet orifice area, and geometry (LID ratio). The results indicate that volume pre-dominates in determining snubber efficiency, while the other parameters become important at small volumes. Geometry has no effect on snubber efficiency. Criteria for an efficient pulsation dampener construction were obtained.

Jan 1, 1971

By D. H. Platt

Data obtained from on-the-site observations have been compiled to describe the equipment and installation methods used for satisfactory suspension roof support in a large-diameter tunnel. Experimental roof bolting was undertaken from June 1950 until May 8, 1951, in the East Delaware tunnel, which is part of the Delaware aqueduct in Delaware and Sullivan Counties, N. Y. Revised suspension-roof-support plans and specifications were prepared during the spring of 1951 by the City of New York Board of Water Supply; these were approved by the State of New York Department of Labor April 13, 1951, and adopted by the City of New York Board of Water Supply on May 8, 1951.

Jan 1, 1952

By Y. J. Wang

The Hardy Cross iterative method is the most popular technique for solving a ventilation network problem with natural air splitting. This method traditionally solves each mesh equation by an approximation during each iteration. Thus, it is interesting from both a theoretical and a computational viewpoint to be able to solve for an exact solution to the mesh equation. Presented in this paper is an algorithm for computing the exact solution to the mesh equation with a variable fan pressure. The algorithm uses signum functions for air quantities to generate an alternative mesh equation in the form of a quadratic equation that has two solutions defined by the well-known quadratic formula. The condition that the derivatives of the alternative and the original equations must be the same provides a basis for the correct choice between the solutions.

Jan 1, 1998

By Kwadwo Osseo‑Asare, Isehaq Al‑Nafai

The hydrometallurgical processing of bastnasite is a well-known process that is used to extract rare earth metals. However, more accurate measures are required to enhance the efficiency of extracting and recycling rare earths. In this work, Pourbaix (Eh–pH) diagrams for La-, Nd-, and Pr-(F)-(CO3)-(SO4)-(Cl)-(NO3)-(C2O4)-H2O systems were theoretically derived to investigate the stability relations during the hydrometallurgical processing of bastnasite. The diagrams for RE-H2O systems show similar trends to the original ones drown by Pourbaix. The stability domains of RE carbonates were presented by RE-CO3-H2O systems with pH range of 4.5–11. In contrast, the diagrams for RE fluorides showed a large stability region of insoluble REF3 (pH ~ − 1.7–12). The decomposition behaviors of REFCO3 were studied by constructing Eh–pH diagrams for RE-F-CO3-H2O system. The stability regions of bastnasite species extend from nearly neutral to basic media (pH ~ 6.5–12). The acid treatment (using H2SO4, HCl, and HNO3) of bastnasite was investigated by constructing Eh–pH diagrams for REF- CO3-(SO4)-(Cl)-(NO3)-H2O systems. According to these systems, REFCO3 can be decomposed at pH ~ 6.5 when treated with H2SO4 and at pH ~ 1.7 when treated with HCl and HNO3 acids. On the other hand, the alkaline treatment of REFCO3 converts it to RE(OH)3 at pH ~ 11. The recovery of rare earths ions was studied with the aid of RE-C2O4-H2O systems which shows a wide stability region for RE oxalates in pH range of − 2–11. This theoretical approach explained the aqueous relations in the hydrometallurgical processing of bastnasite ore and it can improve the practical hydrometallurgical processing of such ores.

Feb 9, 2024

By B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1993

By Carlos Alberto Mendes Moraes

A legislação brasileira prevê que a destinação correta dos resíduos sólidos industriais é obrigatoriedade do gerador. Porém esta é uma das principais dificuldades encontradas, já que o processo produtivo gera resíduos e impactos ambientais. Entretanto, estes resíduos podem ser aproveitados para aumentar a ecoeficiência e como um objeto maior a ecoefetividade, reduzindo os impactos, aumentando a eficiência econômica e ambiental e contribuindo para a sustentabilidade. O setor metal-mecânico igualmente enfrenta a problemática do gerenciamento ambiental, então, o objetivo deste trabalho é avaliar a ecoeficiência e ecoefetividade dos métodos empregados na limpeza de cavacos metálicos contaminados com fluido de corte de empresas metalúrgicas. Foi realizado um estudo sobre a reutilização do cavaco de alumínio, analisando os métodos utilizados, a destinação caso não possível reutilizar e avaliado a ecoeficiência e ecoefetividade. Esta avaliação foi realizada por critérios estudados, onde é possível avaliar métodos como ecoeficientes e ecoefetivos. Na prática foram encontrados somente métodos ecoeficientes e, entre estes, alguns com práticas ecoefetivas. Os resultados evidenciam que a cultura de reparar, reutilizar, reciclar e destinar, ao invés de promover ações como a remodelagem de um sistema produtivo em ciclo fechado onde não há geração de resíduos é ainda mais prático e realístico.

Aug 16, 2017

Operating CIP/CIL gold recovery plants in the arid regions of Western Australia face unique challenges due to water and ore quality issues. The presence of cations of Mg, Fe and Cu metals in water supplies and leached sulphide ores can have considerable effect on plant consumption of lime and cyanide, due to pH buffering and complexation effects. Reagent costs are critical to many of these operations. In this paper, computational modelling is used to analyse a number of process options to mitigate such issues. This requires careful consideration of the chemistry of the process system, and the ability to predict accurately the response of speciation and precipitation reactions to changing process conditions. The Mg-Fe-Cu-CN-H20 system is specifically modelled in this application. The Gibbs Free Energy Minimisation thermodynamic framework has been selected to model equilibrium phenomena. Furthermore, this approach has been extended to the process flowsheet level, incorporating multiple unit operations and recycle streams in a steady-state mass balance model. The Gibbs equilibrium composition module of HSC Chemistry software has been successfully integrated into the commercial flowsheeting package SysCAD. Consideration of the Gibbs Energy Minimisation capabilities of other flowsheeting packages has also been given. This approach has been successful in simulating the aqueous process chemistry typical of such plants. It has resulted in a predictive capability where equilibrium states respond appropriately to process changes. Potential cost savings may be identified by examining alternative process conditions to minimise overall reagent consumption.This methodology may be extended to other hydrometallurgical plants where issues of solution ideality, temperature and other equilibrium processes are sufficiently understood.

Jan 1, 2005

By R. J. Gunderman

Redesigns of the operator compartments on a continuous miner and on a face haulage vehicle are described. The objective was to optimize the compartments within limitations of existing equipment and functional configurations. Both safety and production should be improved through more comfort for the operator and more natural placement of controls. Design guidelines supplied by the Bureau from a previous contract were used along with human factors analyses to determine requirements. Mock-ups were fabricated from layouts and used to refine design details. The new compartments were implemented and the machines evaluated underground. Comments and reactions to both machines were favorable.

Jan 1, 1978

By R Stefansen, T Wisdom, A Nicholson, K Rahal

The challenges of increasingly scarce water resources and the risk of dam failures has seen the mining industry turn to sustainable tailings management solutions such as dewatering and dry stacking. Filtering tailings has been seen in the past as a cost-prohibitive process for larger throughput mines. However, as larger pressure filters are developed, the economic case for filtered tailings has gained traction.Focus has largely been placed on the correct design and operation of the filters. It is critical, however, that the material handling portion of the disposal system is also properly designed and operated. Thorough testing at laboratory and pilot scale to determine the conveying properties of the filtered material needs to be conducted. This testing will insure the material handling system meets the important availability needs of the mine even during periods of variability in the upstream processes and mine plan.The control system must also be robust and flexible in design to compensate for this upstream process variability. The control system needs to allow for different flowsheets including straight filtered tails as well as EcoTails™, a low-energy solution for co-mingling waste rock and filter cake.This paper will present case studies of different material handling solutions, the testing required for them and the lessons learned from each.CITATION:Rahal, K, Nicholson, A, Stefansen, R and Wisdom, T, 2018. Material handling testing and control system requirements for dry stack tailings, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 361–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Weiran Zuo, Emmy Manlapig, Fengnian Shi

The effect of metalliferous grains on electrical comminution efficiency was investigated by comparative experiments using natural rocks and synthetic samples. The result indicated that the existence of metalliferous grains affects the breakage probability and product size distribution of electrical comminution. On average, metalliferous grains increased the breakage probability of particle in the first pulse discharge by 55% and generated finer product at the coarse end. As a result, particles with metalliferous grains exhibited higher energy efficiency than that without metalliferous grain in electrical comminution. A positive linear relation between product fineness and specific energy in electrical comminution was observed. With the assistance of numerical simulation on the electrical field distribution of ore particle, the role of metalliferous grains in electrical comminution is confirmed and the mechanism of metalliferous grains effect is elucidated. Understanding of the effect of metalliferous grains on electrical comminution is important to evaluate the feasibility of applying electrical comminution to ores with different mineral composition, and to understand the breakage behavior in electrical comminution.

Jan 1, 2014

By Karen Tempel

Newmont's Lone Tree Mine is located 30, miles east of Winnemucca in Humboldt County, Nevada. Starting in February 1994 a pressure oxidation circuit was commissioned to treat refractory gold ores. Gold is leached and recovered from the oxidized slurry in a six-stage carbon-in-leach (CIL) circuit. Lone Tree has been able to maintain tighter control' of cyanide addition and reduce cyanide consumption its CIL circuit through the installation of Degussa's Cyplus® CCS Cyanide Control System in the spring of 2000. 'The Cyplus® CCS, along with additional inputs' from plant sensors, has allowed tor a more efficient and effective control strategy over the manual control method used ,in the past. This paper documents the key aspects of the Cyplus® CCS installation; the development of the control strategy, and the benefits achieved from enhanced control.

Jan 1, 1998

By J. S. Bowles

THE martensite transformation in lithium, dis- covered by Barrett,' has been studied extensively by X-ray techniques by Barrett and Trautz,² and Barrett and Clifton.V he present paper reports the results of an investigation into the metallographic characteristics of lithium martensite. Such an investigation has not been carried out before. The spontaneous transformation in lithium consists of a change from a body-centered cubic to a close-packed hexagonal structure with the hexagonal layers in imperfect stacking sequence." As far as is known at present, this transformation can be regarded as being crystallographically equivalent to the body-centered cubic to close-packed hexagonal transformation that occurs in zirconium,5 although stacking errors have not been reported in zirconium. From a study of the orientation relationships in zirconium, Burgers5 as proposed that the martensite transformation, b.c.c. to c.p.h., occurs by a heterogeneous shear on the system (112) [111]. The crystal-lographic principle underlying this proposal is that the configuration of atoms in the (112) plane of a b.c.c. structure is exactly the same as that in the (1010) plane of a close-packed hexagonal structure based on the same atomic radius. The pattern in 2v2 both these planes is a rectangle d X 2v2d where v3 d is the atomic diameter. Thus a close-packed hexagonal structure can be built up from a body-centered cubic structure by displacing the (112) planes relative to each other.* This mechanism leads to orientations that can be described by the relations: (110)b.c.e. // (0001)c,p.h.; [111]b.c.c. // [1120]c.p.h Observations confirm these relations. In zirconium, Burgers' measurements indicated an angle of 0" to 2" between the close-packed directions, while Barrett's measurements on lithium indicated an angle of 3". According to the Burgers' mechanism, the martensite habit plane for this transformation would be expected to be the (112)b.c.c. plane, for this plane would not be distorted by the transformation. One of the purposes of this investigation was to find out whether the observed lithium habit plane agrees with this prediction of the Burgers' mechanism. Experimental Procedure Materials: The lithium was from the same purified ingot used by Barrett and Trautz.² The Bridgman technique was used to produce single crystals. To maintain a temperature gradient in the melt, during the production of these crystals, it was necessary to use a steel mould with a wall thickness of only 0.015 in. Metallographic Techniques: Lithium specimens could be given an excellent metallographic polish by swabbing them gently with cold methyl or ethyl alcohol.? The best results were obtained with methyl alcohol saturated with the reaction product, lithium alcoholate. With higher alcohols the reaction became progressively slower and the attack became an etch pit attack rather than a polish attack. Butyl and amyl alcohols were used for macroetching. After polishing, it was necessary to remove all traces of alcohol from the specimens; otherwise, on subsequent quenching in liquid nitrogen, the alcohol froze to a glassy film. The alcohol was removed with dry benzene. The benzene in turn had to be removed before quenching, but since it does not react with lithium it could be allowed to evaporate. The specimens could then be quickly quenched before they began to tarnish. This operation could be carried out in air on all but excessively humid days when it was advisable to use an atmosphere of dry nitrogen or argon. For examinations at room temperature, the specimens could be transferred directly from the benzene bath into a bath of mineral oil. In mineral oil the specimens oxidized slowly by the diffusion of oxygen through the oil but the structure remained visible for about an hour. Lithium Martensite: Specimens prepared in the manner described above transformed spontaneously to martensite with an audible click when quenched into liquid nitrogen; i.e., M, was above the boiling point of nitrogen (77°K). The disparity between this result and the M, temperature of 71°K, found by Barrett and Trautz, is probably to be attributed to the large grain size and freedom from mechanical deformation of the specimens used in the present work. The relief effects produced by the transformation did not disappear when specimens were quenched from liquid nitrogen into mineral oil at room temperature. This permitted the microstructures to be studied at room temperature where, of course, the martensitic phase was no longer present. Typical micrographs of lithium "martensite" made at room temperature are reproduced in figs. 1, 2, and 3. As anticipated by Barrett and Trautz, the microstruc-

Jan 1, 1952

By J. C. DeSantis

Thin, highly reflective rhodium films with metal compositions greater than 98% (elemental -weight percentage) have been deposited by chemical vapor deposition using Rh(allyl)3 (ally1 = q3-C3H5) in the presence of a hydrogen plasma. Uniform, crystalline films that adhere well to several types of substrates result from depositions at temperatures as low as 150°C. Depositions using H2 (no plasma), or an argon plasma yields material that is amorphous, contains a significant amount (>14%) of residual carbon, and has a dramatically slower growth rate. The composition of these materials does not vary significantly from that of the materials obtained from the in vacuo thermal deposition with Rh(allyl)3.

Jan 1, 1992

By Gerardo Fuentes

The stoichiometry and kinetics of the hydrothermal reaction of enargite in copper sulphate solutions was investigated in the range 140–300 °C, and particle size under 15 and 50 μm. The stoichiometric experiment was performed at 300 °C, using one gram of sample (96% enargite, 4% tennantite) and 100 mL of copper sulphate solution (10 gpl) at 1.2 pH. Enargite reacted completely after 80 min. A solid product was obtained and characterized by XRD. The main product was chalcocite (M) and some traces of djurleite and chalcocite (Q). Tennantite did not react under these conditions. The kinetic experiments were conducted at 140 °C, 190 °C, 250 °C and 300 °C. From fitted data and Arrhenius equation the calculated activation energy (Ea) was 51 kJ/mol. According to the hydrothermal transformations studied, the reactivity of different phases found in the copper concentrates was bornite > chalcopyrite > covellite > sphalerite > pyrite > enargite > tennantite.

By Wolfgang Pietsch

Roller presses were first invented in the middle of the 19th century, for the economical size enlargement of coal fines as fuels. Coal briquettes became quickly accepted for industrial and domestic use giving rise to a large and sucessful industry, particularly in Europe, Japan, and North America. When, towards the middle of the 20th century, coal was more and more replaced by other energy sources, such as electricity, gas, and oil, roller press manufacturers searched for alternate applications of this equipment. In addition to contemporary coal briquetting, in fields such as smokeless fuel and form-coke, it was found that redesigned and modernized roller presses, which are now capable of exerting high forces, are versatile machines for many tasks in mineral processing. Today they are used for: - the "classic" pressure agglomeration and - the "new" high pressure comminution. In pressure agglomeration, the characteristics of fine minerals are improved by forming briquettes or granulated products from compacts. During size enlargement with roller presses briquettes are directly obtained while granular materials are produced by crushing and sizing of compacted sheets. The processes are carried-out essentially dry and often do not require binders other than those inherently contained in the feed and "activated" by the high forces and/or elevated feed temperatures (e.g. hot briquetting). Therefore, no foreign materials (impurities) are added. Another advantage of the technology is, that wide particle size distributions are acceptable or desirable as feed materials, including millimeter or even centimeter sized particles. Plastic particles deform and brittle materials are crushed during pressure agglomeration. A relatively new application of roller presses in mineral processing is the utilization of the crushing effect when brittle materials pass the nip area between the rollers. It was found that this crushing mechanism is very efficient thus saving energy, particularly in grinding circuits handling large capacities. The paper introduces the fundamentals of the process and describes the design as well as applications of modern roller presses in mineral processing.

Jan 1, 1995

By Charles E. Van Barneveld

RBH Note: the following item is a little different than the usual, in that it shows how explosives were used in the past to assist in putting down holes for iron ore prospecting on the early Mesabi Range of Minnesota. The way explosives were used would not even occur to the modern explorationist, given the equipment available today. The reason for the great difficulty in putting down a hole was that the area was covered with debris from the great glaciers of the past (the same ones that carved out the Great lakes). This debris consisted of boulders, clay, sand, and any other imaginable mixture of materials.

Jan 1, 2013

By P. Ravanal, J. Blazquez, F. Ortega, P. Couceiro, J. Navarro

Massive blasting technique is an interesting alternative to optimize mining’s performance by enhancing digging rates and overall operation’s activities, especially when a reduced operational bench width is available. The exploitation of a huge bench through multiple blasts would mean a potential reduction in productivity and higher operational difficulties. In such hard circumstances, combined with complex geotechnical conditions, a full ground vibration analysis for near and far field vibrations are required in order to safely design and conduct the blast. In this paper, a comprehensive case study will be discussed to show how the application of massive blasting techniques was safely implemented in very complex geotechnical conditions. The proposed solution was based on performing a full ground vibration study to optimize blast design parameters, such as charging and timing, in order to fire the complete bench blast in a single shooting event, without compromising the slope stability. Thus, a massive blast with an approximate tonnage of 6.0Mt was successfully designed and blasted, attending all safety and stability criteria defined by the geotechnical and drilling and blasting departments of Minera Escondida.

Jan 1, 2024

By David Seaman, J-P Franzidis, Emmy Manlapig

"A new device has been developed to directly measure the bubble loading of particle-bubble aggregates in industrial flotation machines, both mechanical flotation cells as well as flotation column cells. The bubble loading of aggregates allows for in-depth analysis of the operating performance of a flotation machine in terms of both pulp/collection zone and froth zone performance. This paper presents the methodology along with an example showing the excellent reproducibility of the device and an analysis of different operating conditions of the device itself.The device has been used to investigate the froth selectivity of attached particles. Simultaneous measurements were made using a different froth recovery measurement technique in the same flotation cell. A comparison of these techniques shows that in this case, particles are selectively detached from bubbles at or near the pulp-froth interface.INTRODUCTIONA flotation cell can be considered to operate in two distinct phases or zones; namely the pulp or collection phase and the froth phase. The pulp zone is responsible for the formation of hydrophobic particle-bubble aggregates, whilst the froth phase is responsible for the separation of these aggregates from surrounding suspended hydrophobic and hydrophilic particles. Thus, the froth phase is the grade determining phase in flotation. A measurement of the bubble load (the mass of particles attached to air bubbles in units of mass/volume) will enable the analysis of the performance of both the collection zone at creating bubble-particle aggregates and also the froth zone at separating these aggregates from surrounding pulp.A measure of froth zone performance that has been used extensively in flotation research is the Froth Recovery, Rf, of a particular system. Froth recovery is defined as the mass of particles collected in the concentrate launder by true flotation as a fraction of the mass of particles entering the froth phase. The measurement of bubble load allows for this term to be calculated easily, rather than having to go through the laborious task of, for example, changing froth depths to determine this performance criterion (Contini et al., 1988; Vera et al., 1999b; Feteris et al., 1987)."

Jan 1, 2004

By A. Khan, C. Ciriello

The purpose of this paper is to demonstrate the value of constraint modelling in optimization of mineral processing systems. This will be achieved by first understanding the overall concept of variation and constraints present in any system. Next, the value of using a Constraint Model in optimization is demonstrated through comparison of business cases. The benefit of understanding the severity of constraints and movement of the bottleneck within a mineral processing system will be understood through the use of a case study. Paper will conclude with a summary of all optimization benefits that utilization of a constraint model can bring.

Jan 1, 2015

By R G. Reddy

The complexity in treating environmentally harmful impurities such as As, Sb, Bi from the base metal matte or metal in the smelting stage are responsible for the high cost of the refining process. The impurity capacities (such as arsenic, antimony and bismuth) of slags were calculated a priori using Reddy-Blander (RB) model. The capacity predictions were for a wide range of matte and slag compositions in copper smelting conditions. The calculated impurities capacities and impurity distribution ratios results are in good agreement with the available experimental and industrial slags data. The a priori knowledge of impurities is useful for reduction of energy consumption and enhanced environmental control in the current and future non-ferrous metal processes.

Aug 21, 2024