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By F. Nava-Alonso, E. Pérez-García, A. Uribe-Salas, J. C. Fuentes-Aceituno, A. A. González-Ibarra, E. N. Castillo-Ventureño

"Precious metals cannot easily be recovered from tellurides by the standard cyanidation process. This work assesses the cyanidation of synthetic samples of precious metals tellurides and explores some alternatives for the leaching of these species (i.e. cyanidation in presence of lead nitrate and thiosulfate leaching). For this purpose, three chemical systems were studied: (1) cyanidation of silver telluride and the effect of lead (II) nitrate addition, (2) cyanidation at high alkalinity and high cyanide concentration of a gold-gold telluride sample containing tellurium and tellurium dioxide, and (3) thiosulfate leaching of silver telluride employing cupric sulfate as oxidant and EDTA as complexing agent for copper. Results showed that standard cyanidation dissolves 10.5% of silver from silver telluride in six hours, while with the addition of 100 mg/L lead increased the silver dissolution up to 100% in the same time. The standard cyanidation of the gold-gold telluride sample dissolves only metallic gold in six hours, while when cyanide concentration and pH were increased, gold and gold telluride were simultaneously dissolved. Finally, thiosulfate leaching dissolves 43.1% of silver from silver telluride in six hours.INTRODUCTION Precious metals tellurides are classified as refractory ores due to the difficulties associated with processing them by the standard cyanidation method. The increasing presence of gold/silver tellurides in some deposits around the world, specifically in Sonora, Mexico, requires new approaches to the cyanidation process, or the development of new leaching techniques. Treatments have been proposed for the recovery of gold and silver from their tellurides, including roasting, preoxidation, cyanidation with lead nitrate, and the use of leaching agents other than cyanide (Zhang, et al., 2010; Ellis and Deschenes, 2016). This work presents preliminary results of three options to recover precious metals from pure tellurides: the cyanidation of gold telluride at high cyanide concentration and high alkalinity, the addition of lead nitrate to the standard cyanidation process, and the use of sodium thiosulfate as leaching reagent."

Jan 1, 2017

By Will S. Pettitt

Fracture Network Engineering (FNE) is the engineering design of rock mass disturbance through the use of advanced techniques to model fractured rock masses numerically, and then correlate field observations with simulated fractures generated within the models. Microseismic (MS) monitoring is a standard tool for evaluating the geometry and evolution of the fracture network induced during a hydraulic treatment, principally by source locating MS hypocenters and visualizing these with respect to the treatment volume and infrastructure (Figure 1). The integrated use of Synthetic Rock Mass (SRM) modeling of the hydrofracturing with Enhanced Microseismic Analysis (EMA) provides a feedback loop in which the SRM is constrained by the information provided by the MS data and the in-situ behavior of the fracture network is better understood, leading to informed decisions on future field operations. This paper discusses the technologies used in FNE and some of the developmental challenges we face in order to provide a more efficient and robust application of the approach. One particular challenge is the accurate representation of MS source data within the models (locations, magnitudes and mechanisms), and the ability to correlate these data effectively with field results. This challenge is being overcome by the development of more efficient numerical modeling algorithms, providing simulations in three dimensions at reservoir scale, combined with validation of these algorithms using laboratory and field case studies.

Jun 1, 2012

By T. G. Joseph

The chicken and egg scenario where adverse truck motions cause ground deterioration and poor ground profiles that in turn cause adverse truck motions is a downward deterioration spiral that dominates in our industry. If we can remove one action, the reaction must stop and vice-versa. A simple 'truck to excavator' load data analysis and wireless communication system is outlined in this paper; that will provide visual assistance to the excavator operator in achieving improved load placement and balance in a truck body. In turn this will reduce the subsequent hauler duty cycle adverse motions and g levels that contribute to structural fatigue, higher tkph, reduced tire life and ongoing maintenance of haul roads

Nov 1, 2011

By P. Chu, J. A. Finch

The formation of small bubbles in flotation is usually accomplished by the use of frothers, or sometimes is due to the presence of inorganic salts in the process water. The effective mechanism associated with the presence of these solutes is generally considered to be coalescence inhibition. However, recent work has demonstrated that the presence of frothers and salts also reduces the size of bubble at the initial formation stage. In this paper we adapt the same experimental setup to investigate the time that it takes for a bubble to form; for a known system power input, the energy to form a bubble can then be estimated from the time. The hypothesis is that the presence of frother and salt will reduce the time for a bubble to form, which can be interpreted as an added energy component being derived from the solute. Testing different types and concentrations of frothers and salts, the hypothesis is supported: the mechanical energy required to form a bubble decreases by about 10% in the presence of these solutes.

Jan 1, 2015

By Frank Arthur Forward

FRANK ARTHUR FORWARD was born in Ottawa and attended the University of Toronto, where he received a B.A.Sc. in chemical engineering in 1924. From 1924 to 1929, he was a smelter operator and research metallurgist with the Consolidated Mining and Smelting Company of Canada Ltd. (Cominco) at Trail, B.C. Moving to Australia in 1929, he was assistant smelter superintendent, Mount Isa Mines Ltd., Queensland, until 1934, when he returned to Canada, spend-ing one year as metallurgist with B.C.

Jan 1, 1970

By A. J. R. Smith

"CANADA'S ECONOMY TODAY is about two-fifths larger than it was six years ago, as measured by the total volume of production of goods and services. Such an achievement has been a rare phenomenon in Canada's first one hundred years. Excluding the forced-draft expansions which took place under war-time conditions, perhaps only the first decade of this century recorded a performance of greater dimensions, when, with massive immigration, the opening up of the West and a powerful array of well-de-signed development policies, the country was looking forward confidently to a great future of nation-building in the twentieth century.What makes Canada's over-all economic advance since 1961 all the more remarkable is that six years ago there was virtually no one in this country who anticipated an expansion of such dimensions. Back in the buoyant conditions of 1956-57, perhaps such an achievement would not have seemed beyond our grasp. After 1957, however, Canada stumbled through an extended period of slow economic growth, high unemployment and substantial and widespread under-utilization of its productive capacity. By the early 1960's, conditioned by the emergence of substantial, persistent and pervasive slack in the economy, t h e r e were few Canadians bold enough to anticipate that their economy was about to embark on a Great Expansion. However, this •is, in fact, what occurred. Beginning early in 1961, Canada moved forward into a sweeping advance which grew into the longest and largest peacetime business expansion in Canada's first century as a nation -a truly great expansion by any standard of measurement. This strong thrust has moved Canada into the front ranks of over-all economic expansion among the industrially advanced nations in the 1960's."

Jan 1, 1970

By H. B. Lumsden

This paper is intended to deal merely with the commercial development of some of the principal non-metallic mineral resources in the three prairie provinces- Manitoba, Saskatchewan, and Alberta. Coal is not included in this summary. Building Stone First and foremost, mention may be made of the building stone now being produced at Tyndall, Manitoba. This is a mottled limestone and is declared by experts to be one of the finest building stones in America, both as regards durability and appearance. It has been used very extensively both for exterior and interior work, not only in western Canada, but also in the principal cities as far east as Montreal. The stone is the "'Upper Mottled Limestone", which forms the summit of the Trenton (Ordovician) strata in the Lake Winnipeg basin. Quarries are at present being operated at Garson and Tyndall . The area where this stone is known to be available extends in a north and south direction for a distance of three miles, and the main productive ridge is probably about one half mile wide. The outlook for the future of the industry is extremely promising, as the stone is becoming increasingly popular in Eastern Canada, more particularly for interior work.

Jan 1, 1928

By W. K. Chan, R. Lahaie

"The Suncor Oil Sands Mine located north of Fort McMurray, Alberta, produces about 80000 m' per day of tailings waste which must be disposed of economically in an environmentally acceptable manner. To date, this has been accomplished by impounding the high water content tailings wastes behind large dykes, many of which approach 100 m in height .The dykes are constructed using suitable overburden material stripped prior to the mining of the oil sands feed and/ or the coarse sandy fraction of the tailings waste itself. Although the above is common practice at many mining operations, the large volumes handled and the resultant costs require designs to be meticulously fine-tuned toward the optimum. As a result, considerable effort is expended on planning, designing and construction, and performance monitoring. The lack of precedent experience (Suncor pioneered oil sands mining), coupled with the realities of long, harsh winters and a variety of troublesome site conditions and construction materials, has led to some very unique dyke construction.This paper overviews current tailings disposal plans as welt as some of the key issues related to the design, construction and performance of these large dykes."

Jan 1, 1988

By François Charette

High stress conditions in underground mines push the performance envelope of support systems to their limit. In weak rock masses these conditions lead to large deformation and breakdown of the rock material, while stress release events in hard rock mines can lead to sudden and usually violent rock and support failure. In typical support systems, a combination of different reinforcement and support mechanisms provide the required convergence control and retainment. These systems usually involve a multi-pass support installation. The advantages of a single pass support system are investigated and several bolting combinations are compared. Criteria for design are reviewed and new criteria are proposed to include cost and effectiveness in commonly used engineering approaches. Field observation and testing is used to illustrate the difference between the proposed approach and more conventional systems.

Nov 1, 2011

By P. R. Cook

Thunder Bay Terminals' plant, now in operation, cost about 70 million dollars and was completed on time and under budget. The paper is the project manager's account of this accomplishment. From site selection through feasibility, engineering and construction to realization, he emphasizes the necessary philosophies for the control of time and money. The computer as a tool is discussed, as well as techniques for procurement.

Jan 1, 1979

By Raymond D. Potts

"Minntac is a taconite mining, concentrating and pelletizing operation located near the town of Mountain Iron, Minnesota, U.S.A. It is totally owned and operated by USX Corporation and represents its largest source of domestic iron units. Minntac began producing fluxed pellets in 1988 and has produced both acid and fluxed pellets since then. This paper compares the acid and fluxed pellets produced at Minntac. It reviews modifications that have been made to the plant flowsheet and discusses areas recognized for improvement since the beginning of fluxed pellet production. It also comments briefly on the performance of Minntac fluxed pellets in USX blast furnaces and the future of fluxed pellets at Minntac.IntroductionMinntac was built in three steps with each step designed to produce 6 million long tons of acid pellets per year. The actual production has varied though. Figure I shows the production by year at Mirmtac. Step I began production in 1967, Step 2 in 1972 and Step 3 in 1978. Mirmtac produced 16.5 million tons in 1979 but only 3.5 million tons in 1982 when the facility was shut down for six months because of the lack of demand for pellets. Since the initial start up, Mirmtac has produced over 200 million long tons of pellets. Until 1987, all the pellets produced were ""acid"" pellets. In 1987, equipment to produce ""fluxed"" pellets was installed and tested. In 1988, full scale production of fluxed pellets began."

Jan 1, 1991

By Ben D. Thompson

Cemented Paste Backfill has proven to be of critical importance to the operation of a number of Canadian mines, primarily due to the rapid backfilling rate this method permits. In order to improve the efficiency of this backfill system (i.e. optimize binder contents, fill fence design, and the employment of two stage filling strategies) there is a requirement to better understand its geomechanical behaviour. In response, in-situ experiments have been conducted in long-hole stopes to quantify the evolution of total earth pressures and pore pressures at a series of instrumented points within both the core of the backfill and close to fill fences. The deflection of fill fences as a result of paste loading has been measured and additional instrumentation has also been employed to measure cement hydration, negative pore pressures, and blasting induced vibrations within fresh and cured paste backfill. Installing geotechnical instrumentation within an open long-hole stope can be an extremely complex procedure and this paper details the methods that have been successfully employed. Preliminary results are presented, and the pressures induced by backfill with differing binder contents, at a number of different in-stope locations are considered.

May 1, 2009

High Pressure Grinding Rolls (HPGR) are said to be a good option in new grinding circuits. Due to their low energy consumption compared to other grinding systems such as SAG milling, there is a strong incentive to check their behaviour for certain ore types. With rising energy prices the operation will become even more beneficial in future. As published in the past, the HPGR is claimed to increase the liberation of the valuable mineral component within an ore. An investigation at the research centre of Polysius was conducted to substantiate the liberation behaviour in finish grinding operations. A pilot scale HPGR test unit (POLYCOM MAGRO) with a roll diameter of 950 mm and processing capacity of 80 t/h was used. Grinding tests were completed with a screen and a two stage drying air separation process (SEPOL). Analysis included standard screen analysis, fractional XRF and modern MLA technology. A technique was developed to oppose the amount of produced slimes (resuming bad flotation) against the positive effect of producing high mass fraction at flotation-easy sizes. The paper shows how effective the use of a dry grinding separation could be in terms of production of mass of liberated metal.

Jan 1, 2012

By J. G. Patterson

"The depressive action of sodium cyanide on chalcocite has been investigated and found to be unstable. Flotation results show that with the addition of sodium cyanide to the system chalcocite is initially depressed but rapidly recovers with time, provided there is sufficient oxygen present.lt is proposed that the unstable depression is due to the reaction of cyanide with adsorbed xanthate and copper ions at the chalcocite surface to form soluble copper complexes. When all the free cyanide has so reacted, xanthate anions can then re-adsorb on the chalcocite surface and the flotation will recover. Results are presented to verify the the above mechanism."

Jan 1, 1968

By F. Schulz

NA's primary smelter has continually increased its production output in the past decade, making it necessary to improve the lifetime of the casting moulds for copper anodes. The current throughput of more than 1,100,000 tonnes per year of copper concentrates amounts to an output of about 450,000 tonnes per year of anode copper at NA's Hamburg plant. The anodes are cast on a single casting wheel with 24 anode moulds. Besides the stable chemical analyses, the reproducible geometry of the anodes is an important precondition for the success of the subsequent electro-refining process. The anode moulds are subjected to thermally-induced alternating stress and side reactions with the melt. Typical signs of wear will be shown and discussed. Different processes to produce anode moulds will be introduced and the results in terms of their lifetime and the quality of the anodes themselves will be discussed. Finally an outlook is given on possible efficiency improvements.

Jan 1, 2007

By L. S. Jen

Canadian copper, nickel, zinc, lead and molybdenum mines are characterized by the mining of ores from which more than one metal is recovered. During the 1980s, approximately 15% of the gold, 25% of the zinc, 30% of the copper, 55% of the molybdenum, 80% of the silver and 90% of the lead produced from Canadian mines were produced as co-products and by-products of base metal mining operations. This trend is not expected to change significantly in the near future. The presence of co-products and by-products affects the level of production and the level of revenue from base metal mines in several ways: (I) in general, production of one base metal cannot be expanded or cut back without affecting the amount of production of another metal;(2) the commercial success of certain base metal mining operations depends on the substantial bonus revenues from co-products and by-products; (3) the quality and economic viability of many ore deposits are significantly improved by the presence of co-products and by-products; and (4) while coproduction is critical to the survival of some mines, bonus revenue from by-products can also be life saving to others during economic downturns. For these reasons, deposits with significant co-product or by-product values are likely to continue to be significant targets for exploration and for acquisition.

Jan 1, 1992

By M. Massinaei

Recently constructed circuits have included multiple stages of columns in a variety of applications, from roughing to cleaning. The Miduk copper concentrator (in south-eastern Iran) is one of the unique mineral processing plants which use column flotation cells as rougher. As the bulk of final concentrate is produced by rougher columns, optimized metallurgical performance of these cells is crucial. This paper will present the study and optimization of, a froth washing system of columns. For this purpose, the cross-sectional area of orifices was increased and their orientation altered. Concentrate assay for copper and silica, in addition to bias rate were found to be the assessment criteria. Modification of the wash water system resulted in increasing the purity of rougher and final concentrate. Negative bias and short-circuiting of wash water into the concentrate launder were the main causes of improper froth zone washing in the former system.

Jan 1, 2007

By J. N. Hilton, D. Moffett, E. Barnes

"A recent pilot-plant program carried out at Rio Algom's Quirke uranium mine at Elliot Lake, Ontario is described. The goal of the research was the production of tailings basin effluents which were low in total radium-226. The process tested involved precipitation of radium with barium chloride and sedimentation in plastic-lined settling ponds. Adjustment of the tailings basin overflow from its normal value of pH 9.5 by addition of sulphuric acid to about pH 7.5 was found to give approximately a five-fold improvement in total radium-226 removal. A five-month demonstration test resulted in an effluent with a mean total radium-226 activity of44 pCi/L after 2.5 days settling time and 29 pCi/L after 5 days. The results from the demonstration program are used to propose a schedule of achievable total radium-226 activities where precipitation and sedimentation are employed. The maximum suggested values for 5 days nominal settling time are: 30 pCi/L in an annual mean, 45 pCi/L in a monthly mean. 60pCiIL in a weekly mean and 80 pCi/L in any single grab sample.IntroductionRadium-226 has been removed from effluents at the Elliot Lake uranium mines since the introduction of the first barium chloride treatment system in 1965. Current practice, which has changed little over the years, consists of radium-barium sulphate precipitation by the addition of a low do se of barium chloride to the clear overflow from the tailings basin(l·2l. Provision is made for the precipitate to settle in large natural or constructed ponds and lagoons. The residence time in these ponds, which depends on the site, ranges from 3 to 35 days, with varying degrees of efficiency being achieved."

Jan 1, 1981

By Y. Thibault, L. Morin, R. Cameron, D. Gould

"There are an estimated 50 to 100 million dry metric tonnes of low-grade nickeliferous pyrrhotite tailings in the Sudbury area alone, with an average nickel grade ~0.8% (plus cobalt). Pyrrhotite is a highly reactive sulphide mineral that has the potential to generate acidity; consequently, it is stored in large tailings ponds that require perpetual treatment to avoid the production of acidic drainage. Re-processing this material using bioleaching technologies has the potential to recover valuable metals, while reducing the toxicity, reactivity, and acid generating potential of the remaining residues. CanmetMINING is currently developing a stirred-tank bioleaching process to recovery nickel and cobalt from pyrrhotite-rich tailings. Stirred-tank experiments have been conducted with one tailings sample over a range of pH and temperature conditions, resulting in 80 to 90% and 70 to 80% leaching of nickel and cobalt respectively in 10 days.INTRODUCTION Sulphide tailings may represent a significant financial liability for mining companies as these wastes may produce acidic drainage under some disposal conditions. As a result, the companies must post financial bonds large enough to ensure there are sufficient funds for perpetual management of these wastes. At the same time, there are billions of dollars in metals incorporated into these mining wastes waiting to become valorized. Many sulphide tailings are amendable to bacterial oxidation for metal extraction. Re-processing of tailings using bacterial leaching has the potential to recover valuable metals from waste; and reduce the toxicity, the reactivity, and the acid generating potential of the remaining residue. By reprocessing these wastes there is an opportunity to significantly reduce liabilities and financial assurance bonds, while recovering metal values. There are an estimated 50 to 100 million dry metric tonnes of low-grade nickeliferous pyrrhotite-rich tailings in the Sudbury area alone with an average nickel grade ~0.8% (Peek et al., 2011) plus cobalt and copper. Pyrrhotite is separated from pentlandite concentrates by magnetic separation and flotation. It is already finely ground and has often been segregated from other tailings material, making „mining? relatively inexpensive. This represents roughly (> $100/ton) in contained value, with negligible mining costs. This paper reports on the development of a stirred-tank bioleaching process for recovering nickel and cobalt from pyrrhoitite-rich tailings, which is currently underway at Canmet MINING."

Jan 1, 2017

By K. Barron

"A computer program is described which will analyze the stability of coal pillars. The extent of the peripheral failed zone and the central elastic core of the pillar, the stress distribution across the pillar and its strength can be determined by a ""sliceby- slice"" analysis technique. The program incorporates a brittle/pseudo-ductile transition point so that a pillar may fail by brittle fracture or pseudo-ductile yield. It is shown that:(i) There is a minimum pillar stress below which fracture cannot initiate; hence there is a minimum pillar strength. (ii) In specific circumstances (narrow pillars) , once fracture initiates at the pillar edge it must propagate immediately to the pillar centre. This unstable situation is called ""catastrophic"" failure and might be regarded as a model of a pillar ""burst "". (iii) For wider pillars, the failed zone ex tends gradually into the pillar as the loading increases until it reaches the pillar centre when the pillar is deemed to have f ailed. This is called the point of ""ultimate"" failure.The critical pillar widths to avoid catastrophic and ultimate failure can be calculated.A hypothetical analysis of five rib pillars is given to illustrate the application and the results obtained from the model. The model is then used to analyze three case histories taken from the literature. The first demonstrates the applicability of the brittle/pseudo-ductile failure criteria for Pittsburgh coal. The second compares the pillar strength formulae derived here with those of Salamon and Munro(13) and Bieniawskiou . The final case history compares the model analysis with field stress measurements in a yielding pillar. In all cases the model results are compatible with the case histories."

Jan 1, 1984