Search Documents

By Magnus Evertsson, Johannes Quist

HPGRs have since introduced in the 1980s (Kellerwessel, 1993; Schönert, 1988), now become integral comminution units at several minerals processing plants around the world. Even though a lot of the initial issues concerning performance, availability and wear have been addressed and solved there are still phenomena and aspects which can be improved and understood further. Schönert and Sander (2002) presented experimental results and a mechanistic model including the internal force dynamics between the rollers and the compacted bed. They derived expressions for the pressure distribution involving most of the influencing terms and effects. However, in order to solve the differential equations several of the terms vanish by assumptions. The Schönert and Sander model reflects the experimental data in many aspects but the predicted shear force distinctly deviates from the experimental results at the angular position of the peak pressure level. This finding suggests that the particle to particle interaction and breakage process in the different zones seen in Figure 1 are complex and difficult to model using analytical models. A numerical modelling approach using DEM does not require the same amount of assumptions and simplifications of boundary conditions. Hence such modelling may provide further knowledge and vital understanding. In this paper the breakage process is simulated in order to investigate the shear slip behaviour and how it relates to different operating variables. A laboratory scale HPGR corresponding to the experimental setup used by Schönert (2002) have been modelled in EDEM (DEM-Solutions). The bonded particle model (BPM) is used for modelling quartz particles (Potyondy, 2004). The breakage model strength parameters are calibrated against interparticle breakage experiments in an Instron 400RD compression device. The contact model parameters are calibrated using calibration methods developed by Quist (2015). The floating roller dynamics are modelled using a spring-damper system. Results present insights regarding the interparticle slip behaviour as well as the frictional tangential force distribution on the rollers. The simulated roller pressure distribution shows good correspondence with previously reported findings in the literature.

Jan 1, 2016

By T. Tamagawa

A gaseous chlorination process for hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low temperature chlorination-selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide. In this article, the chlorination phase of the processes is described. Initially, the chlorination behavior of chalcopyrite-concentrate micro-pellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established was used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 1999

By Germán Rodolfo Ocampo Castillo

El presente texto señala la incrementación de la productividad de la mina Xstrata Tintaya -Antapaccay a través del contrato de personal adicional, donde se reemplace a los operadores titulares durante la hora de refrigerio y asi mantener una operación contínua en la mina. Como consecuencia de ello, se incrementará la cantidad del mineral descubierto en la mina y por ende, el costo unitario de las libras de cobre adicional por operación contínua se reduce.

Sep 12, 2011

By N. Ogbonna

A mathematical model for bioleaching at the agglomerate scale is developed. The agglomerate is defined as a unit volume of a heap which contains a solid phase (a size distribution of ore particles), a liquid phase (stagnant and flowing leaching solution) and a gas phase (flowing air and air pockets). Leaching at the level of an ore particle is modelled using a diffusion-reaction equation, and oxidation by attached and detached microbes is treated separately. With the aid of the mathematical model, the effect of particle size distribution on the bioleaching of an ore containing a mixture of chalcocite and pyrite, and a culture of iron oxidizers, is investigated.

Jan 1, 2006

Jan 1, 1969

By Carl W. Lam

The increased obsolescence rate of electronic products has made it evermore pertinent to understand the potential environmental impact of materials choices to help guide electronic waste (e-waste) management and promote awareness of high burden materials. Methods for screening for the performance of materials and their potential burden on human health and the environment can be used to comparatively select constituents of present and prospective electronic products. These methods should be able to yield more robust information when linked to other decision-making strategies where integrated data on consumer preferences, production quantities, and regulatory initiatives are sparse or unavailable. A framework is presented here for generating metrics of ecological toxicity, human health toxicity (cancer and non-cancer categories) and global resource consumption for evaluating environmental impact of materials (specifically metals) in electronic products. The time-dependent impact trends of United States? printed wiring board (PWB) metals usage, principally derive

Jan 1, 2010

By Kerry Gee, Gary Colgan, James Fricke

Introduction Elevated zinc concentrations are observed in groundwater within alluvium adjacent to Silver Creek east of Park City, Utah. The study area is located in a small valley one and one-half miles northeast of Park City, Utah in Summit County, Utah (Figure 1). Although surface water concentrations in Silver Creek are typically less than 1 mg/l, groundwater concentrations have been measured as high as 85 mg/l in a near neutral pH environment. The elevated zinc concentrations in groundwater result from several factors including: (1) dissolution of zinc from tailings exposed at the surface and within the alluvium, (2) oxidizing conditions created by surface/ground-water exchange, and (3) ideal geochemical conditions for the dissolution of zinc-containing minerals. These ideal conditions include readily soluble minerals, available anions for complexation, and lack of available surface adsorption sites.

Jan 1, 2005

By B. J. Vorster

AngloGold South Africa region currently consists of twelve gold plants. These plants use a combined total of $20 million of cyanide per annum. Of this, the major portion (60%) is consumed at two Ergo dump retreatment plants. Historically the primary motivation for cyanide control at Ergo has been one of leach/cost optimization. However, more recently, with the increased public awareness of cyanide in the environment, a secondary but increasingly important motivation for control has been to ensure that only the minimum amount of cyanide is added to the process whilst not compromising leach performance. Following a brief overview of the Ergo process, the methodology in determining the amount of cyanide to be added is described. The paper then traces the developments in cyanide control from very basic manual systems to the current automated control system. In line with the increasingly sophisticated control systems, developments also took place in regards to the method of cyanide analysis. The development of these analysers is also discussed. Whilst cyanide is one of the major drivers, if not the major driver of gold dissolution, it cannot be viewed in isolation particularly with respect to the relationship between cyanide and oxygen as ascertained from the Elsner?s well-known equation. Consequently, in order to control cyanide addition, knowledge of the relative cyanide/oxygen profiles is necessary. Various means investigated at Ergo for pulp oxygenation have therefore been included for the sake of completeness. Finally a comparison is made of the control achieved from the current system compared to the original manual system. The knowledge and experience gained at Ergo is now being used to draw up guidelines for the installation and optimization work at the other AngloGold plants. The net effect of this will be reduced cyanide consumption for the region, which also, apart from the obvious economic benefit, translates into a reduced environ-mental risk.

Jan 1, 2001

By E. J. Haug, K. L. Clifford, K. L. Purdy

St. Joe Minerals Corp.'s Southeast Missouri Mining and Milling Division produces lead, zinc and copper sulfide concentrates at three of its operations. The Viburnum and Fletcher mills have been described in previous papers. The new Bushy Creek mill, dedicated in May of 1973, is an updated version of the Fletcher mill incorporating 8.5 m3 (300 cu ft) lead and zinc

Jan 2, 1979

By César Cánepa

Las especies minerales son los sujetos del quehacer metalúrgico -en tanto, el diseño, la optimización operativa y el monitoreo periódico de una planta de tratamiento requieren de un adecuado conocimiento de las características de los minerales involucrados. En ese sentido, el presente texto señala las particularidades de los minerales (tamaño de grano, composición porcentual y grado de liberación) y su determinación cuantitativa a través de técnicas que ostentan sofisticación, donde la primera característica no se determina mediante técnicas no microscópicas, mientras que las dos últimas son factibles de establecer mediante la microscopía óptica, utilizando la metodología desarrollada por uno de los autores. Dicha metodología es compatible con el entorno instrumental y tecnológico de la mediana y pequeña minería, aunque puede ser utilizada con igual beneficio por la gran minería. Asimismo se presenta dos ejemplos actuales de cómo la aplicación de estudios microscópicos al proceso metalúrgico que se utiliza en la mina Atacocha, un yacimiento polimetálico ubicado en los Andes centrales del Perú, se desarrolla exitosamente en la optimización del proceso.

Sep 12, 2005

Igneous phosphate deposits located in tropical and subtropical regions of the world are characterised by low P2O5 grades, very diversified mineralogy and intensive lateral plus vertical variations in chemical composition, mineralogical assembly, rock texture, grain size, slimes content and morphology plus surface coating of apatite particles. Those variations characterise ore types with distinct behaviour in mineral processing plants. This work reviews the main challenges to concentrate those ores, addressing developed solutions. Apatite concentration requires long chain anionic collectors to conduct reverse flotation of barite (alkyl sulfate) before direct flotation of apatite (sarcosinate, sulfosuccinate and oleate) at basic medium. The long chain collectors decrease the surface tension of the flotation solution (?LV) and a particular value of 51 mN/m was found to promote the most selective separation between apatite/gangue at a particular plant. Effective control of the magnitude of ?LV in industrial plants has not been realistic because there is a lack of reliable instruments to carry out in-situ measurements. Regarding gangue depression by starch, a review is made on possible mechanisms that promote its remarkable ability to depress some minerals (Fe-oxides, ortho plus meta silicates and calcite) vis-a-vis others (quartz, apatite and layered silicates). Flotation recovery (R) of fine (20<R<30 per cent) and coarse (30<R<60 per cent) apatite particles is considerably lower than the recovery of the intermediate ones (R>70 per cent) and inadequate hydrodynamic conditions within flotation cells are the main reasons for that behavior. Once the best hydrodynamic conditions to float coarse particles are not the same to float the fine ones, flotation of coarse and fine particles is commonly conducted at separated circuits in industrial scale. Entrainment of very fine gangue particles is an important source of contamination of apatite concentrates, mainly when weathered ores are treated. In most cases, adjustments in flotation equipment (columns or mechanical cells) promote considerable improvement in the quality of final concentrates.

Sep 13, 2010

"INTRODUCTION While investigating prevention of sabotage and maintenance of production of essential war minerals, engineers of the Bureau of Mines visited more than 1,400 metal and nonmetallic mines, quarries, and open pits in all parts of the United States.The need for, uniform safety practices is indicated by the fact that during 1938-1940, inclusive, the Western Safety Conference, under the sponsorship of the California Department of Industrial Relations, undertook the prepara¬tion of a set of standard safety regulations for the 15 participating political subdivisions. The membership of these political subdivisions is comprised of representation from Alaska, Arizona, British Columbia, California, Colorado, Hawaii, Idaho, Lower California, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming, For the guidance of its own engineers; the Bureau of Nines found it necessary to prepare a set of safety practices that could be used uniformly throughout the United States. These safety practices were compiled from State mining regulations, mining company safety rules, and the experience of Bureau of Mines engineers for more than 3 decades, and represent the best safety practices of the Nation's' mineral industry.The purpose of this publication is to make safety practices available for the non-coal branches of the mineral industry, with the hope that they may assist in reducing accident occurrence. The Bureau will welcome questions and suggestions regarding these practices in order that changes may be made as necessary.Where the adoption of any practice would not materially increase the safety of employees or would work undue hardship on the operator, the Bureau does not recommend such adoption."

Sep 1, 1946

By Kalervo Rankama

UNTIL a few years ago, geological mapping, the study of ore boulders, and different geophysical methods were the principal means used in the systematic search for mineral deposits covered by a layer of disintegration products or soil. These methods have been developed to a high stage of perfection as far as the geometrical definition of the conductor is considered. Use of geophysical methods in prospecting is based on the fact that an ore body differs from the country rock not only geologically but also in its physical properties. The general drawbacks and complications included in the use of geophysical methods are well known to everyone who has been using them, so need not be entered into here in detail. One of the more important ones is the fact that geophysical methods are unable to furnish information concerning the chemical composition of the ore bodies responsible for the indications. Further, the ores of many metals, such as silver, gold, beryllium, zinc, mercury, tin, lead, vanadium, antimony, chromium. molybdenum, tungsten, manganese, cobalt, nickel, and the platinum metals cannot be directly located by known geophysical methods, owing to lack of physical characteristics suitable for distinguishing them from the country rock. Thus it is quite natural that efforts have been made to develop direct methods for prospecting and locating ore bodies of the elements named. Known as chemical, biogeo-chemical, and geobotanical methods of prospecting, these have been much improved during recent years. A brief review of these methods and of some results obtained with them will be presented in the following, on the basis of available information and my own experience.

Jan 1, 1947

By J. H. Nixon

A three phase program evaluated commercial proximity warning devices, developed and designed a microprocessor-based electrostatic field measurement instrument, and utilized this instrument to investigate the electro-static fields about power lines. The Phase I program consisted of test and evaluation of these commercially available proximity devices. The evaluation results were reported in the Phase I report entitlted "Evaluation of Proximity Warning Devices II dated 22 February 1980. The Phase II program resulted in the design and development of a microprocessor-based Distributed Sensor A.C. Electrometer which measures the electrostatic field present at 17 discrete locations along a crane boom. Operator control of the measurement system allows simultaneous electric field measurements from 17 probes, print out of the electric fields measured, and data archiving on magnetic tape for post measurement analysis. Under the Phase III program, electro-static fields around a crane boom were measured by the instrument at 17 high voltage power lines of various voltages and geometries. The electric field data was processed and plotted versus boom distance from the power line. Analysis of the electric field data indicate that the distances at which a single sensor alarm will activate, vary by a factory of 3 to 1. This is due primarily to variations in boom orientation. The results also indicate that in the case of multiple power lines, a single electrostatic field sensor cannot reliably be used to determine the distance from a power line.

Jan 1, 1982

By E. F. Ferrell

Electrowon molybdenum powders and a commercial hydrogen-reduced powder, all with different minor impurities, were investigated by the Bureau of Mines with respect to inherent properties, to fabrication techniques, and to proper-ties of the fabricated sheet. Compared with the commercial hydrogen-reduced powder, the electrowon powders had a larger particle size, a greater flow rate, a higher apparent density, and a lower oxygen content. Sheet materials prepared from the two types of powders showed similar mechanical properties, under the same conditions of heat treatments, except for low-temperature ductility. Yield strengths varied with carbon content, heat treatment, and test temperature.

Jan 1, 1970

By A Giblett, M Daniel

"The Global Mining Standards and Guidelines Group (GMSG) currently supports nine individual industry working groups focused on developing standards and guidelines for the mining industry. In 2013 the GMSG established the Industrial Comminution Efficiency (ICE) working group to develop freely available guidelines for plant operators to quantify the operating efficiency of industrial comminution circuits. This initiative has engaged a diverse group of representatives from mining companies, equipment vendors, consultants and metallurgical laboratories with vast experience and capabilities in the field of comminution. The GMSG has issued the first two guidelines from the ICE working group in 2015–2016, with the third guideline having completed the approvals process and being in the final stages of editing ahead of release later in 2016.Two of the ICE guidelines present methods to quantify comminution circuit efficiency, and a complementary guideline describes best practice methods to collect the necessary samples and data to furnish these assessments. Collectively the guidelines cover sampling, survey data collection, laboratory testing procedures and calculation processes to allow the user to generate a relative circuit efficiency factor for the comminution circuit at the time of survey. The reference energy consumption is calculated considering the measured F80, P80 and ore strength at the time of survey, using either or both of the Bond or Morrell methods presented in GMSG guidelines dedicated to each method. The guidelines consequently provide the end user with practical tools to perform circuit efficiency analysis and to readily quantify the impact of optimisation efforts.This paper presents the content of the three ICE guidelines and describes their intended application.Citation:Giblett, A and Daniel, M, 2016. Global Mining Standards and Guidelines for Determining Comminution Circuit Efficiency, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 3–8 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Robert W. Yokom

As the search for new sources of energy and minerals leads to more remote areas of the country - and the world - the need to plan for adequate housing and community facilities for the construction and operations workforces and their families takes on an importance equal to the mining and processing facilities themselves. A corollary to the need for planning is the increasingly crucial need for development companies to devise effective strategies for dealing with the local communities impacted by these projects. Experience has amply demonstrated the high price to be paid for failure to learn this lesson, a price measured in lost productivity, confrontation with local communities, labor turnover, mental health and other social and eocnomic problems. In Sweetwater, Wyoming, a new industrial activity caused the population to double from 18,000 to 36,000 between 1970 and 1974. During that period industrial productivity fell 25 to 40 percent, cost overruns on the principal new industrial facility exceeded 33 percent, annual employee turnover rates climbed above 100 percent, the local mental health clinic workload increased nine times and complaints to the local law enforcement agency increased 60 percent.

Jan 1, 1981

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of Clay, Gilmer, and Lewis Counties, W. Va. In 1966, almost 1.3 million tons of coal was mined in these counties, of which more than one-half was from the Pittsburgh coalbed. Washability analyses were made of 16 coalbed samples. Of these, only 11 samples could be upgraded to metallurgical quality. For steam or power generation five of the coals were of low sulfur content as received. The remaining samples were generally of medium sulfur content even after upgrading.

Jan 1, 1969

By using knowledge-based technology to create a Virtual Mining Enterprise and integrating it with existing technical and financial computer systems, a gold mining company has been able to reduce the time taken to produce a mine plan from 14 weeks to less than one week. Typically, the mine planning process requires circulating and managing large amounts of information. Even with the use of computers in todayÆs business, this is often still a manual process involving file transfers and individualised spreadsheets. Mine planning also involves understanding and managing large quantities of complex and interrelated variables. Added to this is the ever changing dynamics and constraints associated with the business of mining. These issues not only hamper the planning process but also question the validity and usefulness of the mine plans being generated. By integrating the information and knowledge of the numerous departments involved in mine planning into one core Knowledge Base - so called æone version of the truthÆ, - mining companies are able to overcome these pitfalls experienced in traditional planning methods. Once set up, the Knowledge Base creates and runs a virtual mining enterprise with which to visualise and test various scenarios of mining, business and logistical activities. The final output is an optimised enterprise-wide plan with clear and detailed instructions for each of the divisions of the company.

Jan 1, 2000

By A. W. Popp

After forty years of exploration and development, the heavy mineral sand deposits of the Murray Basin are on the eve of substantial exploitation by Iluka Resources Limited, Southern Titanium NL and RZM/Cable/Bemax, whom plan to initiate mining and processing operations in 2005. A trial mining and processing operation was undertaken on the Wemen North strandline deposit in 2001-2003 by Murray Basin Titanium, a joint venture of Sons of Gwalia and RZM/Cable, which brought to light a number of mining and processing problems which have since been the subject of extensive studies and process development work. The mineralogy of these weathered strandline deposits is complex by industry standards due to the variety of the heavy minerals present, coatings on the mineral grains and the extensive weathering and alteration which has taken place during the past 50 million years. This paper provides an overview of the complex mineralogy that, in turn, dictates the processes that can be used to recover the valuable heavy minerals. The Murray Basin encompasses some 300,000 km2 and has been a depositional basin, often land locked, since the start of the Cenezoic Era. The economic heavy minerals include ilmenite, altered ilmenite, leucoxene of highly variable composition, rutile, and zircon. There are also other heavy minerals present such as cassiterite, chromite, and monazite in quantities that pose both problems and opportunities. The clay content and overburden thickness also play a major role in the selection of the deposits to be mined. Project Services Consultants (PSC) has undertaken the preparation of this paper as part of its ongoing participation in the mineral sands industry and in particular the project development activities in the Murray Basin region currently being undertaken by Iluka Resources. PSC has been involved with the mineral sands business for several years with senior staff having in excess of 30 years global industry experience. The company is well placed to provide a range of services to clients like Iluka Resources in the areas of project development, execution and strategic development and industry advice.

Jan 1, 2005