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By Harry Holle, Ivan Hunter, Darrin Thomson, Gary Johnson

Over the past five years Dominion Mining Limited has directed an on-going effort towards optimising the performance of its milling circuits. The approach has been on a wide front, and has addressed a variety of issues associated with the design and operation of SAG milling circuits. Major projects have been conducted in the areas of flowsheet optimisation, mill liner efficiency, and dynamic circuit performance. As a result the initial designs of many of the Dominion circuits have been modified, mill liner specifications have been rationalised, and a robust automatic control system has been developed. A group-wide approach was taken on most of these projects, resulting in substantial benefits to both the individual operations and the company as a whole. By applying the projects group-wide a significant multiplier effect has been gained on the funds invested in each project. Extensive use of steady state modelling techniques has been made in order to understand the performance of the different circuits, and to highlight the potential areas in which improvements can be made. Liner optimisation has been primarily aimed at achieving predicability of performance, both metallurgical and mechanical. The development of a robust automatic control system has enabled the dynamics of the milling process to be controlled, and resulted in an additional increment in throughput being achieved. The combined effect of these efforts has been to raise plant availability to consistently over 95% (on a long term basis), to improve the power efficiency of comminution (in SAG mills) by 20% or more, and to enhance the dynamic performance such that a more than 10% increase circuit throughput has been demonstrated.

Jan 1, 1993

By A. I. Kalugin, A. A. Abramov, D. E. Kozlov, D. V. Magazanik

Based on theoretical and experimental researches of phosphate and carbonate minerals flotation in the presence of soluable glass at various pH values and sodium silicate concentrations, it has been established that the presence of soluble glass in solution leads to formation of silicate compounds on the surface of phosphate and carbonate minerals causing change in their floatability for the worse. The harmful influence of soluable salts is done by tying of collector as metallic soaps, forming precipitates on the surface of minerals to be floated and causing their depression of flotation, and breaching of the froth etc. Depressing action of slimes and products of interaction with collector depends on the ratio of values and signs of potentials of the mineral surfaces. The possibility of phosphate and gangue minerals separation can be evaluated by comparing the minimum-necessary concentrations of collector required for their flotation.

Jan 1, 2002

By Nick A. Hasenack

A full survey of the laboratory and blast-furnace tests on 2 types of acid pellets is given. From the laboratory tests, carried out in an atmosphere containing hydrogen, it appears that type B, produced out of 100% magnetitic ores, has a far better low temperature disintegration index and a lower reducibility index than type A, produced from a hematite/magnetite mixture. The swelling index, chemical composition and mechanical properties of both types of pellets do not differ significantly. From the blast-furnace test, carried out with a burden consisting of 45% of pellets and 45% of sinter with basicsty ratio about 2.2, and at constant driving rate, it follows that there is no significant relationship between the disintegration value of the pellets and the blast-furnace permeability. If also is concluded that the lower reducibility of the type B pellets leads to a significantly higher coke consumption.

Jan 1, 1975

By B. J. Arnold, F. F. Aplan, R. R. Klimpel, E. C. Jr. Dowling

Residence-time distribution techniques are useful tools in the analysis, characterization and modeling of the performance of processing equipment and circuits. This paper presents the results of both conventional and more-sophisticated residence-time distribution techniques for industrial copper-flotation-circuit data. While conventional techniques provide a description that is sufficient for macroengineering design requirements, the more sophisticated tracer-technique methods give more realistic descriptions of process flows and system effectiveness. It is demonstrated that these approaches can provide highly useful information about different equipment, as well as its configuration and performance.

Jan 1, 2000

By R. L. Bleifuss

The object of this study was to evaluate the oxidized taconites of the western Mesabi iron range and to establish a correlation between the various basic taconite types and their concentratability. This study was made at the Mines Experiment Station of the University of Minnesota under the sponsorship of the Great Northern Railway Company. The initial work included a study of the original mineralogical and stratigraphic facies of the fresh taconite and traced the oxidation and leaching patterns developed during the conversion of this material to oxidized taconite. Subsequent studies have extended this work to include the semi- taconites and also the wash and heavy media ore types widely developed in the area. Each basic, original mineralogical facies or taconite type produces during alteration an equivalent secondary oxidized facies which has a unique mineralogical composition and texture. These control the concentratability of the oxidized taconites. Actually the influence of the original mineralogical composition of the iron formation extends even further and determines whether the most likely product of oxidation and leaching will be a wash ore or a heavy media ore and even to the direct shipping ores where the ratio of hematite to goethite is largely determined by the original taconite type.

Jan 1, 1964

By Bo Arvidson

SALA MAGNETICS, INC. is now operating a 15 tph continuous high gradient magnetic separator, the SALA-HGMS® Mark III Carousel, as part of a complete mineral processing pilot plant installed at Sala's Cambridge headquarters. The Mark III can generate a maximum magnetic field of 18 kG making it possible to process even weakly magnetic, finely ground ores and ore tailings on a continuous basis at the performance level achieved in Sala's cyclic high gradient magnetic separators. Test results on iron ores, clay, and decoppering of molybdenum concentrate will be discussed. Bench scale tests have been performed on all of these materials using the SALA-HGMS® Model 10-15-20 Cyclic Magnetic Separator. A direct correlation may be made between cyclic and carousel results. Sala's Mark III Carousel high gradient magnetic separator is designed to permit scale-up to machines capable of processing two hundred (200) tons of ore per hour and more.

Jan 1, 1976

By I. H. Keith

INTRODUCTION The following papers describe the extraction of nickel in the form of ferronickel from the Dominican laterites. The Falconbridge process was developed initially in the Falconbridge Metallurgical Laboratories and subsequently in several successive stages of pilot plant operation in the Dominican Republic. In the course of this work we came to believe that there is advantage in piloting on site. Mining, metallurgical and geo-political considerations all have major impact and that belief has been borne out by commercial plant experience. Lateritic nickel ores differ substantially, even within the same orebody, in their amenability to extraction methods. The Falconbridge process takes account of the heterogeneous nature of the deposit. Three years of geological field exploration led to ten years of process development after it was realised that the then known metallurgical processes would not give economical extraction from the Dominican ores. In addition to establishing the viability of a novel pyrometallurgical approach, it was necessary to verify design parameters for a very considerable scale-up to prototype commercial operation. The plant was eventually constructed within the original estimates of time and cost. Unique features contributing to the technical and commercial success of the project are described. Additionally, some bold extrapolation based on pilot plant work, eventually proved to be quite conservative. The mine is not a conventional open pit operation, but is perhaps better characterised as an earth moving job. Novel application of mobile equipment led to great flexibility in the mine, where operation of several mining fronts is essential to maintaining uniformity of ore feed to the plant. The practical aspects of almost total acceptance of the oversize run-of-mine material through a high-capacity unit,

Jan 1, 1979

By Harold Wagner, Prakash Donde, Larry H. Heflin

INTRODUCTION The Washington Metropolitan Area Transit Authority is responsible for the planned 166 kilometer (103 mile) Metro rapid rail transit system in Washington, D.C. Some 117 kilometers (72.8 miles) of this system is in operation and contains 30.6 route-kilometers (19 miles) of rock tunneling. To complete the planned system an additional 1.6 kilometers (1.0 miles) of single track tunnels in rock are planned and additional contracts will consist of 4 kilometers (2.5 miles) of twin tunnel, resulting in 8 additional linear kilometers (5 miles) of single track tunnel contracts yet to be offered in soft ground. Three recent contracts in soft ground included the New Austrian Tunneling Method (NATM), along with conventional tunneling, as a bid option. Section E5a, Fort Totten Station and Tunnels, was the only one of the three to be constructed using the NATM option. This is the first application of the New Austrian Tunneling Method in soft ground in the United States. This paper will concentrate on the Fort Totten Station chamber NATM design, construction, and the instrumentation readings and evaluations which lead to an engineering back analysis which allowed a refinement of the bid design, resulting in a faster, more efficient construction. Design of the Fort Totten Station and Lines was done by Sheladia Associates. The design team included Greiner Engineering and Jenny Engineering with Mayreder-Consult of Austria, who was responsible for NATM design and NATM construction consultation.

Jan 1, 1991

By P. Randall, J. Ickes, S. Chattopadhyay

This study was undertaken as a part of developing treatment alternatives for waste materials, primarily waste rock and roaster tailings, from sites contaminated with mercury (Hg) mining wastes. Leaching profiles of waste rock over a range of different pH and oxidation-reduction (Eh) conditions were performed. Since iron (Fe) is present in large quantities in mining wastes, the effect of Fe on leaching of Hg was also determined. Results show that the Hg concentration increased as the pH of the suspension increased until a pH value of 10.65. Thereafter, the Hg concentration decreased sharply. The Hg concentration, in presence of Fe decreased significantly (1/10thto 1/100th). Kinetics results show a relatively slow rate of leaching in presence of ferric ions. The results obtained from the present study are being used to predict the fate and stability of Hg present in the environment, and will therefore, be useful in dictating the nature and suitability of any remediation treatment.

Jan 1, 2003

By P. Somasundarrtn, A. Sivakumar

Flotation of minerals is governed by many processes at the solid/liquid/gas interface, such as adsorption and precipitation of surfactants. In this paper, the basic principles governing these processes and hence flotation are discussed. Also, recent techniques such as fluorescence and ESR spectroscopy which have been used to study in situ surfactant adsorption and to obtain information on the structure of adsorbed layer are discussed.

Jan 1, 1987

By R. J. Good

It is well known that the elimination of impurities such as iron pyrite, shale, clay, silica, etc., from coal, by floatation [Sun, 1954; Aplan, 1983] and selective oil agglomeration [Keller and Burry; 1990] depends on the fact that coal is hydrophobic, and the impurities are hydrophilic. The water contact angle has long been used to evaluate the hydrophobic nature of coal, first by Brady and Gauger (1940), who demonstrated that the contact angle of water on coals increases with rank, and passes through a maximum at about 88% carbon. Brown (1962) found that the contact angle of coal decreased with increasing ash content. Sun, and also Aplan, have reported a direct relationship between values of the contact angle and rank, and have related the contact angle to coal floatability. Horsley and Smith (1951) first demonstrated that the captive bubble contact angle may be used to characterize the hydrophobicity of a coal containing more than 80% carbon DAF, while Parekh and Aplan (1978) have shown that the sessile-drop technique may be used to evaluate the hydrophobicity of coal of any rank.

Jan 1, 1992

By Ernst P. Hall

As a scientist and an engineer whose responsibilities include the consideration of air pollution and its control, I am frequently called upon to answer variations of two basic questions, These questions may I be set forth as: (1) How much air pollution does the coal industry cause? (2) How serious is the air pollution problem to the coal industry? At first these questions may seem elementary and almost trite, but serious consideration of them will show that they are technologically involved and I further complicated by the subjective base to which they must be evaluated.

Jan 1, 1963

By W. M. Schafer

The risk that water quality will be degraded by mining activity can be evaluated using risk analysis techniques. Water quality impacts can occur where water-rock interactions with tailings, waste rock, or leached ore lead to increased loading of constituents into surface or groundwater. Constituent loads contributed by mining facilities are determined by the migration route and chemical evolution of mine water. Mass load contributions from mines can be determined by estimating the prototype pore water in contact with mining waste, predicting the rate and timing of flow, assessing the degree of geochemical attenuation, and modeling chemical mixing with natural surface or groundwater. Mining facility siting and design measures can alter the chemical evolution of mine water by varying the quantity or quality of flow. Stochastic risk management techniques provide a powerful tool for quantitatively identifying the environmental consequences of various siting and design alternatives.

Jan 1, 1998

By Kotaro Ohga, Kiyoshi Higuchi, Zhang Xun Tao

In Japanese coal mines, drivage works of in-seam gate roads are mainly carried out by blasting methods. Changes of methane concentration in gate roads are recorded by centralized monitoring systems in general. To obtain useful information from the recorded data, authors analyzed changes of methane concentration for 3 hours after blastings. As a result, the changes of methane concentration with time can be divided into five distinct patterns. It is thought that appearance of the each pattern depends upon the geological conditions of the surrounding of the headings. Therefore, we attempted to confirm such observations by simulations using mathematical models.

Jan 1, 1989

By D. Farnell

Large semi-autogenous (SAG) or autogenous grinding mills have become the work-horse of the modern high volume concentrator. They typify the economy of scale - fewer, larger machines doing more work, more economically. With fewer machines, equipment reliability becomes of paramount importance. Realizing this, companies installing new or modernizing existing facilities have placed extraordinary emphasis on purchasing a reliable mill. This, in turn, has had a significant impact on mill design. Kennecott And Codelco - Two Different Approaches Last year, two of the world's largest copper producers, Codelco and Kennecott, undertook the modernization of their main grinding facilities at Chuquicamata and the Utah Copper Division (UCD) respectively. Both selected semi-autogenous milling and both, recognized the importance of the reliability of the primary mills. Each, however, decided on a different approach to optimizing reliability. Codelco placed the emphasis on technical innovation in design and opted for a gearless driven mill. Kennecott chose the more conservative approach of active participation and exceptional quality assurance in mill design and manufacture.

Jan 1, 1987

By Ronald L. Wiegel

Success has been achieved in developing mathematical models of rod mills, ball mills and recently to a limited extent autogenous grinding mills. There is also considerable activity in the development of mathematical models of various mineral concentration opera¬tions, such as flotation, magnetic separation and electrostatic concentration. However, at present there is a technological gap which hinders the integration of both size reduction and mineral concentration models into an overall process simulation model. This gap exists because size reduction models have been aimed at describing the size of the product and have not dealt with the equally important problem of identifying the product composition in each size fraction. Without this information the concentration model is ineffective. This situation is especially critical in the simulation of the magnetite-taconite beneficiation process, where a portion of the ore is rejected from the process following each stage of size reduction. Consideration has therefore been given to the merging of a size reduction model and a mineral liberation model to permit prediction of mineral composition as a function of size. The results of this integration of size reduction and mineral liberation models are discussed from both theoretical and practical viewpoints using batch grinding data for a magnetite iron formation sample as a demonstration vehicle.

Jan 1, 1975

Since 1955 Gaspe Mines has produced 144 million tonnes of ore, averaging 0.87% Cu, mined from two open pits and underground workings. In 1994, four exploration drill holes discovered a buried porphyry/skarn Cu-Mo deposit at depths of between 1000 m and 1700 m below the top of Porphyry Mountain. The mineralization and alteration associated with the Porphyry mountain quartz monzonite does not outcrop. A total of 19,500 m of drilling in 12 drill holes has outlined 200 million tonnes grading 0.73% Cu and 0.08% Mo. Mineralization occurs as veins and disseminations of chalcopyrite and molybdenite. Drilling and feasibility studies continue.

Jan 1, 1998

By Tim Q. Haldane

The ability to efficiently process low grade gold ores has allowed the Gold Fields Mesquite Mine in Imperial County, California to expand from a 2.1 million tonne per year rate in 1986 to its present 7.3 million tonne per year processing rate. Increased tonnage demands led to the 1989 construction and start-up of a dump leach pad to supplement the existing heap leach operation, resulting in an excellent opportunity to compare the two processes at the same operation. Additional operating costs associated with the crushed ore heaps are justified through enhanced recoveries, even at very low ore grades. An overview of current operating practices at Mesquite is presented along with metallurgical and economic comparisons between the crushed and run-of-mine ore heaps.

Jan 1, 1990

By R. Froidevaux

Geostatistical estimation techniques were customized to enable forecast of production figures at the Silver Bell uranium mine (Uravan District). Surface drill hole data were used to provide a block model of kriged estimators of average uranium grades. The recoverable figures, such as ore-waste ratio and ore grade, are then deduced from regressive curves previously obtained from underground information and production data. Cross-validations of the entire model were performed and were found positive.

Jan 1, 1981

By Mark Godfrey, Wickus Slabbert, Debra Miller, Dave Dew

Sao Bento Mlnerai;;ao Mine (SBM), located 100 kms northwest of Belo Horlzante, Brazil, was commissioned In 1987t1l to produce 185 kg per month of gold from 240 tpd of refractory sulphide flotation concentrate. The concentrate Is processed by a Sherrill Gordon design pressure oxidation circuit followed by conventional CIL gold recovery process (Flgur .. J). The original plant design foresaw expansion to 480 tpd, and In this regard the acidic effluent neutralisation, CIL and carbon circuits were designed for future expansion to treat the higher tonnage. The pressure oxidation section was sized for 240 tpd with the Intention to double the Installed plant equipment to provide 480 tpd capacity when required. This decision was based In part on the novelty of pressure oxidation to treat refractory sulphide concentrates in 1984 when the process design was finalised. General Mining, Metals & Minerals (Pty) Ltd (GENMIN), has been actively Involved for the past 30 years in the development of bacterial process for the oxidation of refractory gold concentrates; the results of this development program have provided the registered process BIOx®. The successful Implementation of BIOx® technology for treatment of refractory gold concentrates at GENMIN's Fairview Mine In October 1986t2l, as well as the substantial experience accumulated in laboratory and pilot testing of some 40 other sulphide concentrates, Justified reconsideration of the oxidation process best suited to provide the Incremental sulphide oxidation capacity planned for SBM.

Jan 1, 1992