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By Yuanbo Zhang

Zinc leach residues produced by hydrometallurgical zinc plants contain many valuable elements (zinc, iron, lead, gallium, indium silver, etc), while they have not been utilized effectively hitherto. In this paper, a new process of flotation-reduction roasting-magnetic separation to recover these valuable elements from zinc leach residues is developed on a basis of mineralogy investigations of them. The results show that silver concentrate with grade of 4321.6 g/t and recovery of 80.69% have been obtained, using 1750 g/t Na2S as conditioner, 750 g/t ammonium dibutyl dithiophosphate and SN-9 (assistant collector) as combined collector and 100 g/t terpenic oil as frother, if zinc leach residues with 523 g/t silver are floated at pH = 5.0. When the flotation tailings are subjected to reduction roasting at 1100? for 2 h, the volatilizations of zinc, lead and indium are over 96%. After roasted products are treated by wet-grinding and magnetic separation, the grade of gallium and gallium in the concentrates achieved respectively reaches 1805 g/t and 1536g/t, and the recovery of them is high to 94.67% and 93.20%, respectively.

Jan 1, 2006

By Francisco Sotillo

El artículo da cuenta de una investigación orientada a demostrar los beneficios del mecanismo de conminución en una cama de partículas, como ocurre en los rodillos de molienda de alta presión (HPGR) o molinos de rodillos de alta presión (HPRM). Se ha investigado el uso de los HPGR de laboratorio para mejorar la eficiencia de separación de los minerales con alto contenido de dolomita, ultra alto contenido de arcilla y alto contenido de arcilla (kaolinita) presentes en una mena de apatita en operaciones subsiguientes «aguas abajo» de beneficio de diferentes minerales de fosfato de origen sedimentario. La investigación incluye estudios de caracterización de minerales de fosfato dolomítico, datos del modelo físico aplicado por PerUsa EnviroMet, Inc. de HPGR para desarrollar información preliminar de conminución; y evaluaciones de HPGR de laboratorio para determinar los parámetros de chancado (velocidades de alimentación; velocidad y separación de los rodillos; torque, presión y energía aplicables).

Sep 30, 2020

By María Julia Ubillús Mellet

Los proyectos mineros relacionados con actividades extractivas requieren de exhaustivos estudios sociales, económicos y culturales del entorno donde se localizan. Sin embargo, la mayoría de estos son incomprensibles para la población -en tanto utilizan un lenguaje especializado como términos y códigos técnicos. En ese sentido, el presente texto señala cómo la información cualitativa y cuantitativa requerida para los estudios sociales, económicos y culturales, se puede representar y analizar de una manera adecuada a través de la cartografía temática. Así, dicho lenguaje gráfico se convierte en el soporte necesario para la clasificación, jerarquización y representación de las variables, de forma que visualiza la información y mejora el entendimiento de cualquier proyecto para la comunicación con las comunidades involucradas.

Sep 12, 2005

By Marc Piard

In a cool mine, tapping high-pressure lines through reducing valves lowers the temperature beyond remedy. It is the writer's suggestion that, for low-pressure work, law-pressure air ,should be generated in a compressor installed underground adjacent to the work, and that the jacket-water of the compressor should be utilised for re-heating purposes. Such a system of compressed air distribution, designed especially for service in cool mines, is described in the following notes. The suggested system includes a three-wire pole line from the sub-station to the opening nearest to the working face, with a cable connection extending to the latter from the openings; an electrical centrifugal unit; a reservoir excavated in the ground; and a distribution line, re-heated by jacket-water. As regards the reservoir, it may be pointed out that in many mines there are blind or abandoned tunnels that could be used for the purpose. The centrifugal type of compressed air machine is a comparatively new departure, and it was formerly considered that such a machine, operating at less than 1,000 kilowatts per unit, would be commercially impracticable. At the present time, however, these machines are being built in Europe for as little as 400 kilowatts per unit, and as much as 110 lb. per sq. inch pressure. One advantage which these centrifugal machines have over other types is that they may be driven by plain induction motors, without the help of special starters-a consideration of the first importance where the electrical regulations are severe.

Jan 1, 1926

By Robert P. Moodry

It was attempted to revitalize an old sulfide leach dump by increasing the oxygen content within the dump. Compressed air was introduced into the old dump. This was accomplished by drilling 300 foot angle holes into the dump surface with an Aardvark drill which holes are then cased with 1-1/2 inch perforated PVC pipe. Compressed air is injected through these cased holes during a 10 day rest cycle. The second case consists of bedding perforated polyethylene pipe at the interface between the old dump surface and the next Lift of a new dump. Compressed air is then blown through the bedded perforated pipe on a continuous basis while leach solution is applied.

Jan 1, 1976

By Lanny Pasternak

"This article is directed at plant production, engineering and maintenance personnel. Seldom does any industrial operation take the time to study the costs involved in the generation of what is probably their most expensive plant utility energy source.IntroductionIn the typical industrial plant in Canada, a 200 hp, 900 cfm, air compressor costs about $60,000* per year to operate (Fig. 1). In 1989 when BC Hydro embarked on their industrial energy management program Airflow Energy Ltd. were asked to spearhead the “Efficiency Compressed Air” portion of that program with a mandate to perform onsite overview surveys and physical hands-on testing of some 300 selected industrial plants throughout British Columbia for compressor efficiencies and wasteful air leaks (Fig. 2). The program duration lasted until 1995, during which time a tremendous amount of data were amassed relating to equipment types, clients’ operating habits, end-use applications and operating costs.During the past six years, Airflow Energy also performed somewhat similar surveys but on a smaller scale in Alberta, Ontario, the United States and the Republic of China. It was no surprise to find some inherent equipment concerns related to efficiency as well as neglected energy wasteful air leaks, so British Columbia was not alone and the problems appear somewhat universal."

Jan 1, 1996

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Jan 1, 1938

By Robert W. Zimmerman

POROUS SOLID COMPRESSIBILITIES There are four different compressibilities associated with porous solids, each relating the fractional change in either bulk volume or pore volume with the change in either pore pressure or confining pressure. These will be referred to as Cbc, Cbp, Cpc, and Cpp, with the first subscript denoting the relevant volume, and the second subscript denoting the relevant pressure. They are defined as: [ ] Note that minus signs are included in two of the definitions so that each of the compressibilities will always have a positive value. In general, each compressibility depends on the elastic moduli of the matrix material, the porosity, and the exact geometry of the pores. Taking the latter factor into account calls for separate analysis for each different pore shape, which of course can only be attempted for a few relatively simple cases. But lower bounds for each of the four compressibilities can be found, independant of pore structure, in terms of only the porosity (0) and the elastic moduli of the matrix material (any pair chosen from K, E, G and V). The first step is to find relationships between the four compressibilities, starting with the following observation: If a porous solid made of a linear elastic, isotropic and homogeneous matrix material is subjected to uniform hydrostatic pressure of magnitude P on its external and all of its internal (pore) surfaces, the state of stress in the solid will be exactly the same as that which would occur

Jan 1, 1982

By Y. Duraisamy

This paper presents the compressibility of tropical peat reinforced with cylindrical cement column. When a cement column installed vertically in peat, its compressibility was reduced because of the hardened skeleton matrix formed by cement particles bonding with adjacent soil particles in the presence of pore water. The effects of diameter, number of columns and cement proportions in cement columns on the compressibility have been investigated in this study. The results indicated that compressibility index Cc and Ca decreased with the increase in diameter of the cement column. Specimens with 45 mm and 60 mm diameter of cement column were cured for 28 days, after which they were subjected to Rowe Cell Consolidation test. Based on the results obtained, it shows that cement columns can successfully reduce the compressibility of tropical peat.

Jan 1, 2007

By Heinrich Siemes, Christa Hennig-Michaeli

The effect of temperature and orientation on the plastic behaviour of an impure titaniferous magnetite from Palabora (South Africa) has been investigated. Prismatic specimens were axially compressed along [001], [110] and [111]. The strain rate was about 3.10-6 s-1. Trace analyses of glide lines revealed a plastic anisotropy due to glide on several non-equivalent crystallographic planes. At 200 °C {111}<112> twinning, {111}<110> slip and {100}<011> slip have been operative. At 400 °C {111}<110> slip and {100}<011> slip are primary glide modes. {110}<110> slip seems to be a secondary glide mode in the [001] specimens at 400 °C. {III}<112> twin glide generates isolated sharp lamellae. {111}<110> slip produces smooth surface striae. {100}<011> slip is characterized by coarse and partially wavy slip bands. {I10}<110> slip displays faint remarkably equidistant glide lines. The critical resolved shear stresses (CRSS) decrease with rise of temperature. The CRSS ratio of slip on [100) to slip on {lll} increases from 1.1 at 200 °C to 1.4 at 400 °C giving rise to a distinct flow anisotropy of the magnetite at 400 °C.

Jan 1, 1982

By David S. Cahn

For many years the green and dry compressive strengths&apos; of pellets have been, considered as possible criteria of pellet performance during induration. Although widely quoted throughout the industry, little attention has been given to standardizing the unfired pellet compressive strength test or to determining the characteristics of the test. The purpose-of this study was to compare the constant deformation rate test with that using a constant loading rate in addition, the dependence of these tests on such pellet properties as size, weight, and method of balling was to be investigated.

Jan 1, 1967

By Ben L. Seegmiller

The basic compression-yield concept of roof support for mine roadways requires that the mine roof be placed in a state of compressive stress. The compressive stress may be achieved using a support system such as an entry truss or other specialty truss device. Furthermore, the roof must be allowed to yield, but with great resistance when abutment loads are placed on the roadway. The resisted yielding may be provided using a new yieldable steel prop, known by the trade name, YIPP~. The yieldable steel prop can allow as much as 1.5 m[5 ft] of yield, or up to approximately 40% of the opening height, while providing a resistance in excess of 60 mt[66st]. More than fifteen mining operations including coal, trona and hard rock mines have field tested the YIPPI . Present results indicate that the yieldable prop provides a cost-effective alternative to wood cribs, concrete cribs, hydraulic props and other steel prop supports. The paper describes the YIPPI including its unique principle of operation, its applications and actual field performance.

Jan 1, 1992

By Peter J. Scales

The recovery of water for re-use in minerals processing is an important issue in the reduction of water use in mining, as is the dewatering of tailings to reduce the propensity of ?wet? tailings dams. It is common in these dewatering operations to use thickeners whereby polymeric flocculants are combined with the dilute feed to the thickener to aid sedimentation and the subsequent consolidation of particulate materials. Thickeners are the workhorses of water recovery and tailings dewatering and although the basics are well understood, there is still no ability to reliably predict the throughput and underflow density from a thickener based on traditional sedimentation tests and flux analysis. The reasons for the discrepancy between full-scale operations and predictions based on laboratory tests are numerous, including difficulties in mimicking the flocculation conditions experienced in the field and the shear conditions in the thickener. The latter effects are little understood and hard to quantify and include effects due to flocculated aggregate densification, complimentary shear and compressional effects and aggregate break-up. Developing a set of test protocols to quantify the effects of densification, shear in compression effects and aggregate breakup and the subsequent contributions of each to compressional dewatering in a thickening environment has been completed for a simple model polymer flocculated particulate suspension. The data and analysis shows that aggregate densification is a dominant contributor to the difference between observed and predicted behavior based on laboratory tests. A major consideration in the analysis is the fact that common thickener operations are permeability limited and although the various effects are all important, the one that results in the fastest water release is dominant. Of interest also are the shear rate, concentration, and time dependence of the aggregate densification process. A basic model of the process has been developed along with network yielding tests conducted using rheometry. Keywords: compressional dewatering, gravity thickening, rheometry, aggregate densification, raked batch settling

Sep 1, 2012

By M. Hesham El Naggar, Osama F. E. Drbe

"Abstract: The use of micropiles has greatly increased the last twenty years, including applications involving low capacity micropile networks, seismic retrofitting, underpinning of existing foundations and high capacity foundations for new structures. This paper presents a field study of the behaviour of single hollow core micropiles in firm to stiff lean clay. Eight micropiles were installed using hollow bars (76 mm OD and 48 mm ID) with air/water flushing technique and advanced to a depth of 5.75m: six micropiles were installed using 228 mm (9 in) drill bit and two micropiles were installed using 178 mm (7 in) drill bit. All micropiles were instrumented with linear potentiometers to measure the vertical displacement of the micropile head and vibrating wire strain gauges to measure the axial strain at three points along the micropile length. Twelve full scale tests were conducted on the eight micropiles, four monotonic compression, four cyclic compression and four tension tests. Only the results of micropiles tested under monotonic compression is presented in this paper. The full scale load tests and a comparison of the performance of the micropiles with 228 mm and 178 mm drill bit are presented and discussed in terms of load-displacement curves, bond strength and tip resistance. The results showed that the proposed values of bond strength in FHWA give a conservative design of the hollow core micropiles. The micropiles constructed with 228 mm drill bit performed marginallybetter than the micropile with 178 mm drill bit in terms of the ultimate capacity.IntroductionMicropiles have been defined in a variety of ways, but can universally be classified as small diameter (less than 300mm), bored, and grouted in place piles (FHWA, 2005; Bruce et al., 1999; and Scherer et al., 1996). They can sustain axial (compression and tension) and/or lateral loads. Dr. Fernando Lizzi used micropiles in 1952 for underpinning of historic buildings damaged during World War II (Bruce D. A., 1988). Since then, micropile applications have expanded rapidly to include underpinning for existing foundations, in situ reinforcement, and seismic retrofitting and foundations for new construction. In particular, micropiles have graduated from use in low-capacity micropile networks toapplications as single high-capacity foundation.Micropiles capacity is affected by the construction technique, which involves drilling, placing reinforcement, and placing or pressurizing the grout. For example, the drilling method influences the degree of bonding between the grout and the ground, and the placement of reinforcement and the choice of grouting method have an impact on the development of the bonding. Bruce et al. (1997) showed that grout/ground bond is most affected by the grouting method. Based on the type of pressure applied during the grouting process, micropiles are classified as follows (FHWA, 2005): Type A: grout is placed under gravity pressure only using either sand-cement mortars or neat cement grout. Type B: pressures typically in the range of 0.5 MPa to 1 MPa are applied in order to inject the neat cement grout into the drilled hole while the temporary drill casing is withdrawn. Type C: involves two-step process; neat cement grout is first placed in the hole under gravity pressure head only as in type A, and prior to the hardening of this primary grout, a similar grout is then injected via a preplaced sleeved grout pipe at a pressure of at least 1 MPa. Type D: like type C, this type is a twostep process: neat cement grout is placed in the hole under gravity pressure head only (but pressure could be applied in some cases), additional grout is injected via a sleeved grout pipe at a pressure of 2 MPa to 8 MPa once the primary grout has hardened. In some cases, a packer is used inside the sleeved pipe, enabling specific horizons to be treated. Recently, Type E micropile is proposed, which involves"

Jan 1, 2014

By X. W. Yi, Z. J. Li, G. W. Ma

In this paper, the compressive strength and failure patterns of reinforced cemented paste backfill (CPB) were studied aiming to promote the stability of backfilled stopes. The concept of ductile backfill was proposed and a series of unconfined compression tests were carried out on both non-reinforced and reinforced cemented paste specimens. Portland cement (3% to 5% by weight of tailings) and five different types of ductile materials (0 to 0.5% by weight of solids) were employed in this experiment for the specimen preparation. The test results showed that inclusion of ductile materials enhanced the unconfined compressive strength (UCS), reduced the post peak stress loss and transformed the failure behaviour of specimens from classical brittleness to ductility. The strength of CPB reinforced with different proportions of polypropylene fibres was compared. The stress-strain curves illustrated that both cement and fibres contributed to the increase of UCS, but higher strain values at the peak stress were achieved by fibre reinforcement. CT sliced images acquired from X-ray computed tomography (CT-scan) demonstrated that the reinforced specimen developed irregular crevices at the edge of cross sections and gained the capacity of bearing large displacements owing to the mobilised tensile strength of fibres. It leads to the potential of avoiding unexpected falling blocks of CPB when adjacent mining occurs. This finding highlights a strategy to improve the self-supporting capacity of the fill mass with less cement usage and reduce the ore dilution rates when excavating to adjacent stopes.

Jan 1, 2015

By Y. Sugiyama, K. Kitazono, T. Miura, K. Matsuo

"Impact energy absorbing system for automotive is an important technology. Open-cell porous aluminum alloys were manufactured through Powder Bed Fusion (PBF) process. Compressive properties of the porous aluminum alloy depend on the cell structure as well as the porosity. The authors manufactured two ordered cell structures, truncated octahedron and rhombic dodecahedron, and one disordered cell structure, random Voronoi structure using a 3D-CAD software. Compression tests revealed the anisotropic deformation of the porous aluminum alloy with ordered cell structure. On the other hand, the porous aluminum alloy with disordered cell structure showed relatively isotropic and uniform deformation, which is suitable for energy absorbing applications. Therefore, controlling the disordered cell structure designed by Voronoi diagram enables to develop the advanced porous aluminum alloy having various mechanical properties.INTRODUCTIONAdditive manufacturing (AM) process enables to manufacture near net-shape mechanical parts. The AM technology is typically focused on titanium alloys due to their high specific strength and biocompatibility (Attar, 2014). Recently, aluminum alloy parts can be manufactured through selective laser melting method (Leary, 2016). Metal foams or porous metals are lightweight cellular materials having closed-or open-cell structures (Banhart, 2001). Aluminum foams are focused on as an energy absorbing material for transport industries (Baumeister, 1997). The purpose of the present study is to investigate the optimal cell structure of open-cell porous aluminum alloy manufactured through AM process. Most previous researches on the AM aluminum lattice structure has been considered ordered and periodic cell structures. On the other hand, classical aluminum foams manufactured through cast or powder metallurgical processes have disordered and heterogeneous cell structures (Körner, 2000). The authors use a concept of Voronoi diagram (Moukarzel, 1993) in order to manufacture various cell structures."

Jan 1, 2018

By Marc. A. Meyers

The analysis of the phenomena involved in the determination of the compressive strength of iron-ore agglomerates leads to the identification of the important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compression axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments is due to internal voids of varying sizes, that act as stress-concentration sites. Two novel testing procedures are proposed. The first consists of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents significant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1981

By M. A. Meyers, P. P. Meyers

The analysis of the phenomena involved in determining the compressive strength of iron-ore agglomerates leads to the identification of important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compressive axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments u due to internal voids of varying sixes that act as stress-concentration sites. Two novel testing procedures are proposed. The first consults of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents vacant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1984

By Eduardo Luiz Sales Marinho

A Fábrica de oxigênio da AMT produz gases O2 e N2, utilizados no processo de produção de aço. Neste processo de fracionamento de ar, existe um compressor de ar que é responsável pela captação do ar atmosférico. Este compressor é do tipo centrifugo de 4º estágios de compressão, fabricação Hitachi, e tem capacidades de vazão de 114.000 Nm³/h e pressão de descarga 5.4 Kg/cm². Em Novembro de 2012, foi realizada inspeção no compressor e identificado trincas nas pás do impelidor do 4º st e perda de espessura de parede das pás do impelidor do 3º st de compressão. Houve perda da confiabilidade de operação do equipamento, sendo necessária uma ação para correção do problema. Depois de identificado a causa raiz das trincas,foi decidida a compra de dois novos impelidores com modificações no material para aumentar a resistência à corrosão. Na aquisição dos novos impelidores havia duas possibilidades: 1) Adquirir novos impelidores junto ao fabricante original do equipamento; 2) Adquirir novos impelidores por processo de engenharia reversa (levantamento de desenhos da peça desgastada para fabricação de uma nova) em conjunto junto com empresa especializada. Este trabalho irá mostrar os critérios e considerações que levaram a AMT decidir pela compra de novos impelidores por “Engenharia Reversa”, bem como, suas vantagens e riscos assumidos.

Sep 25, 2017

By Jason M. Ryan

"Along with recent advances in computer technology have come cost-effective systems desiiedto evaluate fragmentation distributions through digital images of particles. In mining operations andmineral processing plants, important data from these systems is obtained through monitoring sizedistributions at key stages of the comminution process. Blast engineers apply this technology as atool for the validation of empirical fragmentation models so that predicted results are more meaningful."

Jan 1, 1998