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By Kazuteru Tozawa, Robert G. Robins

"The stability of calcium arsenate is discussed in relation to the possible misuse of lime in the treatment of gold processing waste waters. Stability diagrams have been derived and experimental results cited to show that calcium arsenate has a higher solubility in neutral to alkaline solution than has previously been recognized and this solubility is further enhanced by the presence of carbon dioxide, bicarbonate or carbonate.IntroductionThe removal of arsenic from gold mine waste waters has been of interest for more than thirty years, but with the recent emphasis on clean water standards there has been renewed activity in relation to that problem. The processing of gold-bearing sulphides which contain arsenopyrite and other complex arsenic sulphides is well established. Initial roasting to oxidize the sulphides leaves the arsenic in the form of both arsenic and arsenic, in which forms it is soluble in the subsequent leaching stage. Further oxidation of the leach liquors is required before the well-established procedure of precipitating calcium arsenate with lime, which is carried out despite an immense lack of knowledge of the calcium-arsenic-water system.The solubility product and free energy of formation for Ca3(AsO4)2, which are to be found in recent and reliable sources of data, originate from the work of Chukhlansev, whose experimental determination of the concentration of calcium from the solubility of calcium arsenate in solutions of various pH yields the results plotted in Figure 1. This is the work which has resulted in a wide acceptance of the ""insolubility"" of calcium arsenate and the use of lime to stabilize arsenic in that form.Laguitton attempted to further elucidate the chemistry of the lime addition method for treating arsenical waste waters from gold processing operations. The low solubility product for Ca3(AsO4)2 was the basis for his examination of likely chemical equilibria in the system. Laguitton and other workers have not considered atmospheric carbon dioxide as an important component in this system."

Jan 1, 1982

By P. E. Weidmark

"PART I - Published PapersBallivy, G., and Dupuis, M., ""Laboratory testing for the design of grouted rock anchors""; Proc 6th Pan Am Conf Soil Mech Found Eng; Lima; 1:277-291; 1979.Ballivy, G., Ladanyi, B., and Gill, D., ""The effects of moisture content on the strength of fissured rocks""; Proc 1// 1ntnl Congr 1.A.E.G.; Madrid; //:2:7-16; 1978.Baumgartner, P., and Stimpson, B., ""Development of a tiltable base friction frame for kinematic studies of caving at various depths""; Int J Rock Mech Min Sci Geomech Abstr; 16:4:265-267; 1979.Bawden, W.F., and Roegiers, J.-c., ""Discussion and interpretation of the mathematics governing radial flow in a single horizontal rock fracture""; ISBN 07727-7002-6; Dept Civil Engng publication 79-11; Univ Toronto: 134p;1979.Chatterji, P.K., Smith, L.B., and Insley, A.E., ""Construction of Saline Creek Tunnel in Athabasca oil sand""; Can Geotech J; 16:1:90-107: 1979.Coates, D.F., and Gyenge, M., ""A case history of pit slope design""; Proc 4th ISRM Congr; Montreux, Switzerland; Sept 1979; 1:Theme IV:591-596; 1979.Crawford, A.M., and Curran, J.H., ""A dynamic direct shear machine for determining the time-dependent behaviour of rock joints"": Dept Civil Engng publication 79-08; Univ Toronto; 1979.Crawford, A.M., and Curran, J.H., ""A displacement discontinuity approach to modelling the creep behavior of rock and its discontinuities""; Dept Civil Engng publication 79-09; Univ Toronto; 1979.Crawford, A.M., and Curran, J.H., ""A higher-order displacement discontinuity element""; Dept Civil Engng publication 79-10; Univ Toronto; 1979.Cruden, D.M., ""A computer-based system for rock mass description""; Proc 1// Intnl Congr I.A.E.G.; Madrid; //:2:155-159; 1978.Cruikshank, D.J., and Curran, J.H., ""A.B.LE. approach to modelling of fluid flow in fractured rock masses""; Proc 7th Cdn Congr Appl Mech; May 1979; Sherbrooke, Que; 887-888; 1979."

Jan 1, 1980

By Charle Lawrence, Murray E. Blanchard

"A significant addition to Canada's commodity export transportation capabilities is being built by Ridley Terminals Inc. on Ridley Island in the Port of Prince Rupert on British Columbia's north coast.Site preparation began in early 1982. By the end of 1983 the terminal will be receiving coal from two major new mines being developed in B. C.'s massive $2.5 billion northeast coal development.The RTI terminal will have initial capacity to transfer 12 million tonnes of coal a year from railcars to storage and to ships. Capacity will be doubled to 24 million tonnes as market opportunities are developed.The challenge of building this $220-million facility in less than 24 months, the benefits Canada has received from the work the project is generating, and the long-term faith in Canada that this project represents, are all part of the excitement which surrounds the Ridley Terminal and northeast coal developments.RIDLEY TERMINALS INC. (RTI) is building a very significant addition to Canada's commodity export transportation capabilities. The facility, on Ridley Island at Prince Rupert, on the north coast of British Columbia, is a key link in British Columbia's northeast coal development which in itself is a massive undertaking involving investment of some $2.5 billion. The entire project is making a substantial contribution to Canada's economy at a time when such contributions are sorely needed.The development is creating employment, not only in British Columbia where its various parts are being created by mining companies, railways and others, but also across the country where suppliers are manufacturing a wide variety of good s and equipment for the development's participants.The RTI terminal is no exception. It is a critical cog in this mega project's large transportation system and its construction is contributing substantially to job creation and to other economic activity, in the Prince Rupert area and in many other parts of British Columbia and the rest of Canada."

Jan 1, 1983

By P. A. Riveros

The literature on the arsenic disposal practices of the metallurgical industry and the long term stability of the disposed arsenic compounds were reviewed from a Canadian perspective. The review was complemented with visits to selected operating metallurgical sites to obtain information on their specific arsenic disposal practices and the behaviour of their impounded residues. The arsenic disposal procedure currently favoured by the industry involves the formation of an insoluble ferric arsenate compound which is allowed to sediment at the bottom of tailings or residue ponds. It has been shown recently that this poorly formed crystalline compound is similar to ?arsenical ferrihydrite? which is ferrihydrite containing strongly adsorbed arsenate anions. Despite concerns about its long term stability on thermodynamic grounds, arsenical ferrihydrite appears to be stable for many years in the proper environment which includes a slightly acidic pH and oxidizing conditions. A high Fe/As ratio and the presence of heavy metals appear to increase the stability of arsenical ferrihydrite. High temperature operations, such as those encountered in the autoclave treatment of refractory gold ores, are conducive to the formation of scorodite, FeAsO42H2O, and/or a series of ferric arseno-hydroxy-sulphate compounds depending on the solution composition. Scorodite has several advantages over arsenical ferrihydrite as a disposal compound including a lower iron demand, a higher density and a greater thermodynamic stability. New procedures have been developed to generate scorodite at ambient pressure. These procedures would offer significant reductions in capital cost because of the elimination of the need for autoclaves. Lime precipitation which was widely used in the past is being abandoned as a result of strong evidence showing that calcium arsenate compounds decompose slowly in contact with atmospheric CO2 to form calcium carbonate and soluble arsenic acid. In all cases, the long term stability of the disposed arsenic compounds depends on a number of factors including disposal site characteristics, particle crystallinity and size distribution, the presence of complexing agents and the effect of bacterial activity.

May 1, 2002

By J. Jara

Oxygen, ozone and air were evaluated in the oxidation of ferrous iron in the presence of hydrochloric acid ranging from 0.1 to 4 M HC1. Stoichiometric coefficients were determined through mass balances of gases and ferrous titration. The molar ratio ferrous to ozone increases from two at 0.1 M HC1 concentration to six at 4 M HC1. For oxygen the same ratio is constant and equal to 2 and it is in agreement with other works. The stoichiometric coefficient of hydrogen ion was not defined due to the effect of hydrolysis of ferrous and in particular ferric ion on measuring acid concentration by titration with sodium hydroxide. Agitation, gas flow and pressure contribute in the utilization of gas. A technique to compare the gas efficiency at several conditions is discussed and it is based on the relationship between oxygen and ferric during time. There is a strong compromise between gas efficiency and ferrous conversion. Oxygen efficiency decreased with time due to ferrous depletion. The gas efficiency ranged from 3 % (low level of agitation) producing 25 g Fe(III)/h to 12 % at 1000 rpm with 60 g Fe(III)/h converted. At 405 kPa absolute the oxygen efficiency was in the range of 80 % producing 300 g Fe(III)/h. The replacement of chlorine with oxygen to enrich molybdenite concentrates by reducing copper to less than 0.2 % was evaluated. Oxygen can be employed in batch or continuous operation and it can treat molybdenite concentrates with high variation of copper content. The dissolution rate is mainly controlled by oxygen addition in which utilization of oxygen plays an important role. Improvement on safety and environmental conditions is feasible by using oxygen instead of chlorine gas. The economics indicate good opportunities to implement oxygen without significant modifications to the actual circuit and enough benefit when oxygen is well used.

Jan 1, 2007

By H. Al-Kazzaz

The effects of laser power and joint gap on the welding quality of 2-mm butt joints of ZE41A-T5 sand castings were investigated using a continuous wave 4 kW Nd:YAG laser system and 1.6-mm EZ33A-T5 filler wire at a welding speed of 6 m/min and surface defocusing. The smooth weld profiles with the minor welding defects were obtained at a laser power of 4 kW and joint gap of 0.3-0.4 mm. The hardness values in the fusion zone are similar to those of the base metal but there is a drop in the heat-affected zone after a natural aging of 18 months.

Jan 1, 2006

By A. E. M. Warner, A. Vahed, P. J. Mackey

In the decade 2002 to 2012 some 6.7 million tonnes of new copper concentrate production capacity was brought on line, corresponding to 2 million tonnes of contained copper. This increase in concentrate supply necessitated the commissioning of a number of new copper smelters as well as the modernization and/or expansion of existing plants to meet the demand. This paper gives an overview of the copper extractive industry, reviews recent copper production trends and changes in the copper industry, including an examination of pyrometallurgical and hydrometallurgical technology developments. WorleyParsons has supported a number of the projects involved in these developments and this role is briefly discussed. The paper introduces a number of ideas related to possible future directions of the copper industry.

Jan 1, 2014

By Donald Lindell

Safety Share ?Dad receives fryer for Christmas 2009 and makes delicious sweet potato fries ?When the oil fryer was pushed back on the stove for cooling, the back edge comes into contact with the stove top controls, unknowingly activating the cooking element, family leaves kitchen. ?Faint smell of smoke from the melting plastic alerted the family; teenager arrives first and pulls the fryer forward causing oil to spill onto hot stove and burst into flames that reach the microwave ?Teen runs for sink to grab pan of water but is stopped by Dad ?Dad opens refrigerator, grabs baking soda and pours it on fire, extinguishing flames Lessons 1.DO NOT USE WATER ON GREASE FIRE 2.Where is the baking soda in your kitchen?

May 1, 2010

By R. Butar-Butar, J. Mosher, G. Banini, J. Hollow, A. Villanueva

The effect of High Pressure Grinding Rolls (HPGR), as a preceding stage to a conventional ball mill circuit at PT Freeport Indonesia’s C1/C2 concentrators, has been studied in terms of downstream grinding efficiency and circuit performance. When milling the product from the HPGR, mill capacity increased by 21% for the same product grind size, when compared to processing similar ore from a conventional crushing circuit. This achievement is a result of several reasons, among them: reduction in feed size (F80), fines generation beyond the proportional reduction in F80, reduction in ore hardness induced by HPGR comminution mechanism, optimization of the recycle system of the HPGR and ball string optimization in the ball mill circuit given the new feed to the mill.

Jan 1, 2012

By Bennett McLaughlin

The Penna Shaft is the deepest single?lift shaft in North America. AGNICO-EAGLE started sinking the Penna shaft in 1995 with a hoisting plant capable of hoisting 1 800 tonnes per day from a 2 240-metre deep shaft. Exploration success at depth lead to the replacement of the existing double drum hoist by another double drum hoist capable of hoisting 7 000 tonnes per day. The use of another double drum hoist, instead of a Blair Multi-Rope winder, to hoist 24,5-tonne skips was only made possible by lowering the safety factor. This paper describes recent experiences at Penna and in South Africa, and examines the possibility of extending the double drum hoisting system to a depth of three kilometres.

May 1, 2003

By Jason A. McLennan

Conditional bias is an infamous problem with estimation methods including kriging. Changing estimation parameters will mitigate, but not remove, conditional bias. The conditional bias of kriging is well understood; however, there is widespread confusion in the literature and among practicing geostatisticians regarding the conditional bias of geostatistical simulation. There is no conditional bias of simulation when the simulation results are used correctly. The correct use of simulation for recoverable reserves estimation is to (1) generate multiple realizations conditional to all available data at a small scale, (2) linearly average all realizations to the chosen block size and (3) calculate the probability of each block being ore and the ore grade of each block. The ?probability of ore? and the ?ore grade? are conditionally nonbiased.

May 1, 2002

By W. Lo, M. Brothers, G. Oprea, G. Richard, T. Troczynski

Magnesia-chrome and chrome-magnesia are the most used refractories in contact with iron-rich non-ferrous smelting slags. The corrosion by slag always brings chromium oxide into the slag, causing the precipitation of crystalline phases at the process temperature. This secondary effect of the chromium-bearing refractory dissolution was studied in this work, emphasizing the effect of the other chemical components of the slag at various temperatures. The experimental results showed that the presence of chromium and lead contribute, although in different ways, to the formation of complex spinel phases and their precipitation at temperatures in the range of 1250-1400°C. The XRD and SEM/EDS results were discussed for refractory-slag mixes containing 0-20% Cr2O3 and 0-11% PbO.

Jan 1, 2004

By Richard Hurteau

Design and validation of an integrated guidance system for articulated ground vehicles is investigated. The development of an autonomous industrial vehicle must take into the account the specific geometry of these vehicles; they can be composed of a tractor with 1 or 2 trailers or of articulated type like LHD. Moreover the tractor-trailers type vehicles can have on-axle hitch configuration or positive/negative off axle configuration. The path-tracking of a tractor-trailer vehicle in restricted space is presented and discussed in this paper. Recent results obtained in simulation and validated by experimentation are also presented. These studies can lead to better ways of maneuvering an articulated vehicle in a restricted space or automatically executing of docking and parking maneuvers

May 1, 2002

By Larry T. Yano, Gerald T. Handford

"Tailings Engineering has the responsibility for planning and coordinating tailings disposal and for ensuring the stability of the tailings dyke. The inclusion of both the planning and geotechnical functions in one team has resulted in greater efficiency in the design and planning process. Major challenges in tailings disposal facing Syncrude are in the areas of: (1) sludge disposal; (2) instrumentation and monitoring; and (3) liquefaction. Meeting these challenges will have a significant effect on the cost effectiveness and reliability of the mining operation.IntroductionThe size of the tailings disposal operation has led to the establishment of a large engineering team devoted solely to the disposal of tailings. This paper discusses: the tailings disposal operation, the role of tailings engineering, the organization, inter faces, and the present and future challenges with respect to tailings disposal."

Jan 1, 1990

By Eiichiro Mizushima

Catalyst systems comprising (Ph3P)AuCH3 and acid co-catalysts were found to be highly efficient for hydration of alkynes to give ketones. Methanol was the best choice of solvents. Introduction Hydration of carbon-carbon unsaturated bonds is one of the environmentally benign routes to the carbon-oxygen bond formation. Hydration of alkynes forming carbonyl compounds, an important variation in this category, is a well known reaction which has been extensively studied. The reaction by acid-catalysis is the most conventional method, while it is applicable only to electron rich acetylenes to obtain satisfactory yields (1,2). The hydration of simple alkynes usually requires another catalyst (co-catalyst), typically a mercury(II) salt (3), which is inconsistent with the guiding principle of Green Chemistry (4).

Oct 1, 2003

By S. Malkin, Z. Shi, H. Attia, D. Chellan

An experimental investigation is reported on creep-feed grinding of a nickelbased alloy (IN718) using conventional aluminum oxide grinding wheels. Straight surface grinding expe.riments were conducted on nickel-based alloy blocks over a wide range of grinding conditions with straight oil as- grinding fluid applied at high pressure. Grinding power, forces, workpiece surface roughness, and radial wheel wear were measured. Specific material removal rate as high as 64 mm2/s was Used without burning the workpiece, which can be attributed to the extremely low specific energy of 12.6 J/mm3. It was found that the grinding wheel under the present test conditions had a strong capability of self-sharpening as indicated by the stabilized power, forces, and surface roughness after an initial short transient.

Jan 1, 2006

By T. Kagawa

Ever-increasing demands for non-ferrous metals owing to population growth and improvements in the standard of living in the world, under the constraint of limited availability of natural resources, would easily make us imagine that more efficient and sustainable developments in mining and smelting activities are required in the near future with due consideration for environmental concerns. In order to realize the efficient and sustainable development of mining and smelting activities and operations, the following issues are indispensable: (1) to investigate the up-to-date pollution control technologies of mine and smelter, (2) to promote those technologies, (3) to develop technologies which are environmentally friendly. This paper discusses the recent technologies for environmental conservation/prevention and their diffusion in the world, and also the key technologies required for the most desirable sustainable development.

Jan 1, 2007

By Marcotte P.

Introduction Pneumatic jackleg rock drills are commonly used in underground mining operations. These tools are known to expose their operators to hand-arm vibration levels in the order of 20-35 m/s2 weighted (Wh). Thus, the majority of the workers who have cumulated several years of jackleg rock drill operation are affected by related health problems such as Raynaud's syndrome or carpal tunnel syndrome. Up to now, no efficient personal safety device was available to protect pneumatic rock drill operators against hand-arm vibration (HAV). To address this problem, an anti-vibration handle prototype for jackleg drills has been developed in a previous study. Then, a multi-partner project was launched to refine the prototype and commercialize an effective anti-vibration handle for pneumatic rock drills.

Feb 1, 2008

By Alastair J. Sinclair, Asger Bentzen

Abstract - A simple linear model for interpreting duplicate analytical data for a range of values is described. The conceptual model can be quantified using a reduced major axis model rather than the inappropriate traditional least squares approach. The reduced major axis parameters (slope, intercept) and associated errors provide a quantitative basis for: (1) defining bias, and (2) comparing results within laboratories, between laboratories and between sampling/analytical methods. Application of the linear model must be preceded by extraction of obvious outliers or small groups of values that have an inordinately large impact on values of the statistical parameters defining the model. In addition, consideration must be directed to the presence of more than one population of sampling error, as in the case of multiple styles of mineralization being sampled.

Jan 1, 1998

By J. A. Hillier

The staff of the Hudson Bay Mining and Smelting concentrator have developed a new type of reagent feeder. Several factors encouraged the development of such a system: varying heads caused by the mixing of ores from several mines, the increasing number of flotation circuits operated and reagent feeding stations remote from the flotation operator's work area. The reagent feeders also had to be compatible with future plans for reagent control from an on-stream X-ray analyzer and computer system. The new feeder is a positive-displacement pump set to deliver a constant volume per stroke. At a remote panel, the feed rate is altered by changing the time between strokes. The feeders have been found to be reasonably trouble-free and accurate to less than 2 per cent error.

Jan 1, 1973