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By K. Svens, M. Lahtinen, L. Lehtinen

"Outotec's direct leaching process is an atmospheric leaching process for sulphidiczinc concentrates. The direct leaching process, based on special leaching reactors developed by Outokumpu and leaching know-how, is the most economical way to produce electrolytic zinc. The newest industrial-scale application of Outotec's direct leaching process will be started up in 2008 in China at Zhuzhou smelter. The process isintegrated to the existing production plant, replacing part of the old production facilities by modern technology and increasing the production capacity significantly. The process equipment supplied by Outotec includes also tailor-made reactors designed on the basisof the work and experience of Outotec Research Centre."

Jan 1, 2008

By S. P. Singh

"The geological features of a rock mass have a direct influence on its blasting characteristics. It has been observed that perimeter control techniques provide excellent results in massive crystalline formations but may give poor results in weak and or highly jointed formations.A field study was conducted with the objective of understanding the role played by the geological features of a rock mass in producing and controlling blast damage. The field work involved the assessment of blast damage at several operating mines and the blasting of drift rounds in a geologically dominant rock mass.The effect of rock strength, rock quality designation (RQD), joint parameters and hydrogeological conditions on blast damage is described below. The influence of number and thickness of weak layers on blast damage is also discussed below on the basis of quantitative data. In addition, critical particle velocity ranges for damage to different rock types have also been outlined in this paper."

Jan 1, 2001

The uphole bench extraction strategy at EKJV Management Pty Ltd?s Raleigh Mine, requires simultaneous horizontal and vertical exposure of paste filled stopes. In order to prevent excessive ore dilution, the paste fill must be of sufficient strength to prevent failure during exposure. A numerical modelling methodology has been developed to accurately simulate the initial stress distribution within paste filled stopes, together with the strain-softening loading response of paste fill material. Due to the narrow orebody width and high deformation behaviour of the host rock mass, high closure strains are likely to cause a stiff, brittle fill material to undergo crushing failure upon exposure. The stability of paste fill exposures at the Raleigh Mine was determined by conducting a series of three-dimensional numerical models that incorporate the extraction, filling and exposure sequence of paste filled stopes. Stability charts for 2.5 m and 3.5 m wide simultaneous horizontal and vertical exposures have been derived based upon the numerical modelling results. Implementation of the stability charts has proved successful in limiting the amount of ore dilution from paste fill and provides a basis to optimize paste fill cementation and stability throughout the life of the mine.

May 1, 2007

Block caving is an underground mining method for the profitable extraction of massive, low-grade orebodies. Lately, it has become the mining method of choice, for many mining companies, because of depleted high-grade orebodies, and declining metal market prices. Block cave mining, however, still faces several challenges. Lack of access to the cave remains a major issue in understanding the rockmass response to mining for method optimisation. Improving our understanding of the rockmass response to caving will lead to safer and more productive operations. Combining large datasets from multiple sources with virtual reality scientific visualisation (VRSV) is a viable alternative to understanding complex cave behaviour without access to the cave. This is achieved using immersive environments with the ability to view complex multi-dimensional data (beyond 3D) graphically. VRSV offers a unique platform where it becomes possible to immerse the multi-disciplinary experts, and/or management team, in a virtual mine environment for quick decision making and fast resolution to conflicting conclusions. The underground mining system is complex due to multiple interrelating factors such as geology, excavation geometries, stress and time. Block caving is even more complex than most underground mining methods due to the network of tunnels required, and the use of induced stress, among others. As a consequence of the complexity in the block caving environment, it is vital that the mining system is analysed holistically, as a system, rather than optimizing individual factors one at a time. This paper presents a customised software module developed for use in the Advanced Visualisation Interactive Environment (AVIE) at The University of New South Wales (UNSW), Australia, to enable VRSV investigation into block cave mining systems (BCMS). This approach has the potential to provide a better understanding of the effect of time in in rock engineering, which has proven to be an important factor in hard rock mines (Ma & Daemen, 2006; Malan et al., 1997; Suorineni, 2010) but never validated. This work back analyses the early undercutting phase of a case study block caving operation with the view to understanding time/sequence effects. There is evidence that heterogeneous rockmass time-dependent behaviour governs the seismic response of the rockmass following undercut developments.

Jan 1, 2015

By M. E. Rossi, J. E. Camacho

"Geostatistical conditional simulations are becoming increasingly popular as tools that provide models of uncertainty at different stages of a mining project. They have been used as grade control tools in daily operations to assess the uncertainty of mineable reserves at the project’s feasibility stage, and to assess mineralization potential in certain settings. Other applications include assessment of recoverable reserves, resource and reserve classification, and drill hole spacing optimization studies. All large-scale applications of conditional simulations intend to benefit from the correct (or accurate) characterization of uncertainty, adequately describing the variability observed from the data and its effect on the final objective.The objective of this paper is to compare the ad-hoc uncertainty model provided by a traditional classification scheme with the probability intervals resulting from a conditional simulation model. It is argued that the uncertainty model derived from the use of classification schemes is of little practical use to the mining company or operation. The paper emphasizes differences in uncertainty based on the size of the mining unit considered, the extraction method, and local geological differences. Most importantly, it discusses confidence intervals for these mining units, as compared to the relative precision envisioned by a typical classification scheme.The application described in this paper is taken from a medium-sized Cu open pit and underground mine in northern Chile, and demonstrates the impact of several variables on the resulting conditional simulation models. It also compares a more traditional resource classification scheme applied, and the wide difference in local confidence intervals for each mining unit."

Jan 1, 2004

By Norman A. M Macleod

FOR the past seven years, all flotation at the Britannia mill has been done in Forrester Air-Lift cells. Prior to 1931, the roughing and part of the cleaning operation had been performed in four 21-cell and two 14-cell M.S. machines. The resulting economies in reagent, power, maintenance, and general operating costs, and the increased recovery, more than justified the exclusive use of the Forrester machine. About three years ago, the possibility of still further improving the efficiency of the flotation section was the subject of considerable discussion and experiment. Arising from these experiments, tests were made of the practicability of using a cell of greater depth than that of any pneumatic or mechanically-agitated machine in common use. Cells were constructed with depths of 7 .5 feet, 10 feet, and 15 feet, and, in all cases, a very definite improvement in operation was indicated. The cell now being used in the mill treats from 5,500 to 6,200 tons of dry feed per day. It is 100 ft. long by 5 ft. wide by 8 ft. deep, and has replaced a total length of over 500 feet of standard Forrester machine. The choice of a depth of 8 feet was governed by the type of blower which was available-in this case, a Roots-Connersville blower, driven by a synchronous motor and delivering 6,000 c.f.m. of free air at 4.0 pounds per square inch. At the Chelan Division of the Howe Sound Company, where a new mill was recently built, all flotation is carried on in cells 10 feet deep, with good results.

Jan 1, 1938

By J. Grignon, C. Fleming

It is possible to reproduce the performance of an operating CIP or CIL plant in the laboratory, in small scale batch kinetic tests, coupled with mathematical models that translate kinetic data into predicted steady state gold profiles across multi-stage adsorption circuits. Once the performance of the commercial plant has been mimicked by the model, the plant operating parameters can be varied systematically in the model, and the likely response of the plant to the step wise change can be determined. In this way it is possible to inexpensively optimize the operating conditions of an existing plant, with no disruption to plant operations and no economic risk to the mining company. This approach had been adopted by IAMGOLD to optimize the performance of their Rosebel CIL plant following several major expansions in mill capacity since 2004.

Jan 1, 2011

By C. O’Hara, S. Roy, K. Swedburg, J. Katchen

"New Gold Inc.’s New Afton concentrator commenced operation in June 2012, producing a copper-gold-silver concentrate. During the first two years of operation, various optimization efforts have improved mill throughput, recoveries and concentrate grade. Daily mill throughput has increased 20% above the design rate. This was achieved through more consistent instantaneous feed rate and size distribution from the mine reclaim stockpile, higher pebble crusher reliability, changes to the SAG and ball mill grinding media sizes, larger SAG grate openings, reduced SAG discharge screen-deck aperture size and an increase in the maximum ball mill power draw limit. Metal recoveries at New Afton are primarily limited by liberation in the coarser size fractions; therefore, improving the grind size at a given mill throughput has been the main means of improving recovery. The average rougher flotation feed F80 size was reduced from 175µm in Q1 2013 to 165µm in Q1 2014, while the average operating mill throughput increased by 25%. Other flotation circuit changes focusing on recovery improvement include the addition of froth crowders to the rougher cells and the use of a stronger frother. The average concentrate grade increased from 22% Cu in Q1 2013 to 25% Cu in Q1 2014. This was achieved by redirecting the flash flotation concentrate stream to the regrind circuit and by the addition of lime to the cleaner circuit.This paper describes the above improvements made at the New Afton mill. The paper describes the objectives, timing and end result of each area of improvement.IntroductionThe New Afton Mine is situated approximately 10km west of Kamloops, British Columbia, 340km north-east of Vancouver. The mine has a moderate climate, access to transportation and electrical infrastructure, nearby fresh water supply, and close proximity to industrial and mining service businesses. The population of Kamloops is around 90,000 with most mine employees living in or around the city."

Jan 1, 2015

By The Staff

WE were requested to make a digest of our original grinding report, Fine Grinding Investigations at Lake Shore Mines. This digest is much easier to read than the original report, but it lacks the experimental 'evidence' found in the first report which, in many cases, is much more interesting and educational than the conclusions derived from it. In the course of rewriting the paper, we noticed several new angles on the test data which had not occurred to us previously. From the data included in the report and other tests not published, calculations were made which indicated a line of new test work. These tests, among other things, more than suggest a technique for designing the length of mills, the position and number of classifiers, and the total loads a mill should carry.

Jan 1, 1941

By L. Li

The backfilling of underground stopes is a common practice throughout the mining industry. The stresses imposed by the backfill on the surrounding rock mass need to be assessed because of their influence on ground stability and on the hydro-geochemical response of the fill material. There is, however, a complex interaction between the relatively soft backfill and the much stiffer adjacent rock mass. In recent years, the authors have presented results from investigations conducted on stress distributions (obtained numerically and analytically) in and around backfilled stopes with (sub)vertical walls. In this paper, the influence of stope inclination and of backfill properties is evaluated. Results indicate that, in general, the vertical and horizontal stresses in inclined stopes are close to, but somewhat smaller than the stresses in vertical stopes. Nonetheless, significant differences can be observed in some cases, especially for the vertical stress along the inclined central line and along the hanging wall. It is further shown that neglecting deformability in limit equilibrium analyses is an acceptable assumption. However, Poisson?s ratio and the dilatancy angle, usually neglected in limit equilibrium analyses, may have significant effect on the stress distribution. Results also confirm that the backfill strength parameters (cohesion and friction angle) are critical factors required to properly evaluate the stress distribution, at least within a certain range of parameter values.

May 1, 2007

By R. K. Collings

The annual production of mineral and mineral-based wastes in Canada is conservatively estimated to be 400 million tons. Over 90 per cent of this amount is waste rock or mill tailings from the mining and mineral processing industry. The remainder are slags and ashes from the metallurgical industry, and sludges from the chemical industry. Because of impurity content, remote location, or both, most wastes have limited usefulness and, indeed, are a liability in that they must be transported to waste disposal sites and contained therein. Certain mineral wastes do, however, have potential value. Some contain small percentages of metals that may be economically recoverable with price increases; others consist of mineral material that may be used for such purposes as road base, construction aggregate, railroad ballast, and in the manufacture of bricks or blocks. Increased interest has been shown in mineral wastes in recent years. This paper reviews the types of mineral wastes available in Canada, briefly describes a number that have potential value, and notes possible uses and related research by CANMET and other organizations.

Jan 1, 1978

By A. A. Brant

Self-potential methods are based ?on measurements on the surface of voltage distributions caused by natural sub-surface oxidation phenomena. The attempt is made to. correlate voltage minima or maxima with the location of mineral materials or geological conditions which may give rise to such naturally produced spontaneous potentials. Any orebody undergoing oxidation is a source of electric current. Ground waters carrying free oxygen attack the upper surface of the body, rendering this the positive pole of a galvanic cell, with the lower portion of the body the negative pole and the surrounding weak acidic waters the electrolyte. Current flow is from positive to negative through the orebody and negative to positive through the electrolyte, i.e., through the surrounding rock. The upper end of a steeply dipping, tabular orebody is hence indicated as lying below the point on the surface where the largest negative potential is observed(l). From its basis, it is apparent that the self-potential method was developed primarily for ore exploration.

Jan 1, 1942

By C. Larsen, I. Orford, L. Strah, M. Renaud, P. Radziszewski

"An AG/SAG mill was commissioned at the Brunswick mine concentrator in October 1998. This paper discusses the original shell top hat liner design for the bi-directional AG/SAG mill, observed liner wear, subsequent liner design modifications, and benefits.The original liners were chrome-moly steel Norsteel with rubber grates and rubber-lined pulp lifters. The design was based on experiences of other AG/SAG mills and recommendations by the liner supplier, Norcast. Liner design modifications were made in an iterative fashion after observing the wear rate profile of the liners; over ten liner sets were implemented. Shell liner design improvements were supported by a design of experiments approach in conjunction with discrete element method (DEM) charge motion simulations. Design optimization took into account lining costs and impacts on operating performance. The team approach to the liner design improvements process is described with emphasis on the application of the design of experiments. The liner wear history and mill operating performance are presented."

Jan 1, 2005

By Ho-Sung Yoon, Jyothi Rajesh Kumar, Chul-Joo Kim, Sung-Don Kim

A recovery process for rare earths (REs) such as dysprosium and neodymium from the leach liquor of permanent magnet scrap (PMS) was developed. The two hydrometallurgical routes namely liquid-liquid extraction (solvent extraction) and selective stripping were implemented. The present study deals with the separation and recovery process development by using organo-phosphorous based extractant di-(2-ethylhexyl phosphoric acid (D2EHPA) as reagent for REs processing. Initial studies considered the influence of time on the extraction process, as well as pH and extractant concentration effects. This suggested the aqueous mechanism and separation factors played a role in process during development. McCabe-Thiele diagrams for extraction isotherms were developed. Counter current extraction (CCE) using various phase ratios influenced metals separation. Maximum loading capacity of the D2EHPA was determined. The loaded organic generated by the CCE process was water washed followed by a scrubbing process to remove the other metal ion from targeted metal. Finally, a stripping process was tested using various mineral acids.

Jan 1, 2015

By D W. MacFadgen

THE operating advantages of the longwall retreating system of mining, as opposed to longwall advancing, have been well known for many years. Although retreat walls have been successfully worked in the past in some of the collieries of the Dominion Steel and Coal Corporation in the Sydney, Picton and Cumberland areas, the adoption of longwaIl retreating as the general sys-tem of mining has not been attractive in the Sydney field, due to the time and expenditures required to drive roadways to the boundary. In addition. difficulties in maintaining effective ventilation on the faces, especially under conditions of low barometer, have made the operators in the field hesitant to adopt this as the general system of mining. The development of a machine capable of rapid entry drivage has made possible the driving of the necessary road ways to the boundary at a moderate cost, completely changing the picture and making a retreat system more attractive.

Jan 1, 1961

By Willie van Niekerk

As mining projects get larger and more complex there is a need to examine the use of project management techniques developed for large construction projects in order to ensure completion of the project on time and budget. In recent years the construction/civil industry has sought new methods to ensure that multimillion dollar projects involving multiple contractors, working in an increasingly legislated work environment, are delivered to the clients satisfaction. The paper describes these methods, which range from program management to systems and tools to gather all project information such as schedule and cost, and relates how these can be applied to large international mining projects. The paper also describes the benefits that an independent project manager can bring to a client or owner?s team by setting up the relevant organization and controls together with the appropriate contract and procurement strategy.

May 1, 2009

By J. G. Manchuk, M. Thurston

"The degree of uncertainty associated with a natural diamond resource is important to quantify from the time of discovery through the production lifetime. Data collection occurs during the discovery, exploration, delineation, and production or recovery phases. Quantifying the relationship between data and uncertainty is an important component of project valuation. The value of data is measured as their potential to reduce uncertainty if they are collected. A method is developed using Monte Carlo simulation for predicting resource uncertainty and valuing data during critical phases of development, particularly discovery and exploration. The technique is applied to diamond pipe deposits.RÉSUMÉ Il est important de quantifier le degré d’incertitude associé à une ressource diamantifère naturelle, depuis le moment de sa découverte et durant toute la durée de l’exploitation. La collecte de données se fait durant les phases de découverte, d’exploration, de délimitation, et de production ou de récupération. La quantification de la relation entre les données et l’incertitude est une composante importante de l’évaluation du projet. La valeur des données est mesurée en tant que leur potentiel à réduire l’incertitude si elles sont recueillies. Une méthode a été développée qui utilise la simulation de Monte Carlo pour prédire l’incertitude de la ressource et évaluer les données durant les phases critiques du développement, surtout celles de la découverte et de l’exploration. La technique est appliquée à des gisements de cheminées diamantifères."

Jan 1, 2015

By A. E. Flynn

THERE is at the present time a revived interest in amalgamation, due to the number of mines starting up, usually on high-grade ore, and utilizing this relatively cheap and convenient means of recovering gold, more especially in their initial stages of production. The marked increased use of the amalgamation process has revealed a dearth of amalgamators and there is no doubt the art of amalgamation has stood still for a generation or two and is not readily applicable to the modern practice of milling gold ores. Mill operators of long experience are learning the art for the first time and are giving it intelligent study, and considerable testing and research work is now being undertaken Most millmen consider amalgamation a simple process, and so it is when we have a clean ore with coarse gold, specially when stamps are used for crushing. In treating Nova Scotia ores by stamps and amalgamation, recoveries of 95 to 97 per cent are common and easily obtained. So-called 'under-water feed' is almost universally used in Nova Scotia and is quite beneficial. The water is supplied through jets between the dies and below the die surface and maintains this space as a live trap which catches the gold particles before they are overground and spoilt for amalgamation. With this method, the portion of gold recovered in the battery is higher than usual and often amounts to 80 per cent of the total gold in the ore, the remaining 20 per cent being caught on the plate. As a continuous amalgamator, the simple plate cannot be excelled. Some of the modern devices having moving or covered and not very accessible plates, which cannot be readily inspected and dressed to keep them in condition, do not give the best results in service. An exception might be drawn in the case of amalgamation of very heavy ore or concentrate which would bank up unless the plate is carried at such a steep inclination as to weep mercury. Difficulties in stamp-mill amalgamation are encountered when acid water is used or when grease is present. Also, certain sulphides and graphitic and talcose ores give trouble, resulting in poor gold recovery and high mer-cury loss. The older literature on gold milling deals with the common troubles of this type and the old-time amalgamator was well able to take care of day-by-day difficulties. When the difficulties were unsurmountable, the ore was classed as 'refractory' and other processes were used.

Jan 1, 1939

By G. N. Carlson, C. H. Hazelroth, D. R. Dorrance

"Located on the north shore of the St. Lawrence River at Pointe Noire, Quebec are the agglomeration and ship-ping facilities of the Wabush Mines complex. Here, the specular hematite concentrate from the Scully Mine is received for further processing. Modern facilities for handling the ore, either to the 1plant or to stockpile, provide quick and efficient operation of the ore receiving station. Physical preparation of the ore for balling is accomplished with regrind ball mills, filters, bentonite crushing and drying facilities, pumps and related conveying circuits. Rotating table feeders deliver the reground and de-watered ore from storage bins to balling drums, where green ball or green pellet formation is achieved. The green balls are then conveyed to the indurating section. Three Dravo-Lurgi travelling grates, producing a total of 6,000,000 long dry tons of pellets per year, are used in the indurating phase of the operation. These grates, having 38 windboxes and firing at a temperature of 2,500°F, harden the pellets for shipment to various blast furnaces throughout the world."

Jan 1, 1969

By S. Steinlechner, G. Schneeberger, J. Antrekowitsch

The recycling of steel mill dusts is getting more and more important. The costs and requirements of land filling are rising and companies are interested in new recycling strategies. The rising of sustaina¬bility hand in hand with the high rate of valuable metals in these residues supports new research activities on the recycling sector. Especially zinc but also iron and lead are economical factors due to the treatment of steel mill dusts. This paper gives a small overview of fundamental studies concerning the chemical and physical composition of these dusts. Furthermore aggregates for the reduction of these dusts in the liquid phase are introduced and compared. The Flash-Reactor, the TBRC-Technology (Top Blown Rotary Converter) and submerged arc furnaces and there use for melting and treatment of these dusts are in the center of interest of this paper. The final conclusion gives an overview of possibilities for reduction of filter dusts in the liquid phase.

Jan 1, 2011