Search Documents

By John Convey

"IRON ORE was first smelted in Canada about the year 1736 at Les Forges, Quebec -a most appropriate name for such a historic locale. During these early years of the 18th, 19th, and first quarter of this century, about six million tons of ore were mined and employed in the manufacture of items ranging all the way from kettles, stoves, and cannon for the early settlers to weapons of war for the allied armies of World War I.But this symposium on iron ore is not concerned with this early period. Instead, it is concerned with the iron ore industry of today -an industry which will soon be-come one of the two most valuable mineral industries in Canada.The subject in its broad geographic and economic aspects will be introduced by Mr. Buck; Dr. Harrison will describe the geology and origin of the principal iron ore deposits; Dr. Downes will go into beneficiation as it applies to iron ores; and Mr. Gertsman will discuss primary processing. The symposium will not deal with the steel end of the industry, because that phase itself could well form the subject of a symposium."

Jan 1, 1955

By M. W. Lewis

A mine's inherent capacity is dictated by factors such as equipment, design, people, processes, and environment. Actual production may approach, but never surpass, the inherent capacity limit. The inherent capacity ceiling can only be increased through re-engineering. Autonomous haulage systems have the potential to significantly increase a mine ’s inherent and realized capacity. Realized capacity may be maximized through the optimization of soft factors such as the processes, behaviours, and organizational systems, controlling asset utilization, availability, and performance. Truck shovel dispatching systems revolutionized the utilization of mobile assets. High-precision global positioning systems (HP-GPS) are increasingly being adopted to optimize equipment performance. Real-time maintenance management systems have the potential to revolutionize equipment availability and significantly reduce cash costs. This paper explores some of the solutions available to mines to increase their inherent capacity and maximize their realized capacity.

Jan 1, 2004

By M. W. Lewis, B. Sambirsky, J. Werner

A mine’s inherent capacity is dictated by factors such as equipment, design, people, processes, and environment. Actual production may approach, but never surpass, the inherent capacity limit. The inherent capacity ceiling can only be increased through re-engineering. Autonomous haulage systems have the potential to significantly increase a mine’s inherent and realized capacity. Realized capacity may be maximized through the optimization of soft factors such as the processes, behaviours, and organizational systems, controlling asset utilization, availability, and performance. Truck shovel dispatching systems revolutionized the utilization of mobile assets. High-precision global positioning systems (HP-GPS) are increasingly being adopted to optimize equipment performance. Real-time maintenance management systems have the potential to revolutionize equipment availability and significantly reduce cash costs. This paper explores some of the solutions available to mines to increase their inherent capacity and maximize their realized capacity.

Jan 1, 2004

By Fabien Miller

Automation technologies are increasingly envisaged to improve underground mining productivity. However, the technologies need to be used and adopted gradually in order to get the best benefits. This paper presents the technical and operational aspects of autoguided production vehicles at Brunswick Mine. During 2001 Noranda?s Brunswick Mine has successfully commissioned an automated haulage zone where two optically guided trucks transport ore from a remotely operated chute to two orepasses. Operational advantages include increased system capacity and enhanced safety and comfort for the operator. The data obtained up to now indicate that the system can operate reliably in mine production

May 1, 2002

Vale Inco?s Coleman Mine 153 Orebody is a narrow vein deposit with a dip that varies from 30 to 70 degrees. It has a strike length of 1200-feet and the current mining extends from the 4250 level to 5100 level. The primary mining method is mechanized cut-and-fill although drift-and-fill is also used in wider sections of the ore zone. The ore body is divided into six main mining horizons with an average of three mining blocks on each cut. There are some interesting rock mechanics challenges related to mining upward from the 4550 level and these challenges are increasing as the mining front progresses toward the 4400 level. The mining of the 4550 block is currently at cut 13 whereby the crown pillar thickness is approximately 60-feet. Significant factors including increased stress levels in the crown pillar, the change in the orebody dip at this level and a recently indentified geological structure in the footwall, have all combined to introduce seismic activity in the footwall of 4550 level. Closer studies revealed a consistent trend of seismicity that was further examined with core logging and Acoustic TeleViewer technology. The data from these assessment tools disclosed a geological structure that is influencing the mining environment. This paper reviews the seismic analysis for the 4550 level mining zone and the subsequent procedures used to locate the new geological structure. The paper also discusses the key mining practices used to successfully mine cut 13 of 4550 level and briefly reviews the studies that are underway to up-date the mine design for continued extraction of high-grade ore in a safe and productive manner.

May 1, 2009

By Claude MacDonald, John H. Ashburn

"IntroductionIndustrial growth and technological change over recent years had been accompanied by two major sources of concern to management and employees: (a) increase in occupational injury and illness and the resultant costs involved; and (b) equipment damage and breakdowns in concentrated production lines causing more extensive loss potential.Due to economic factors, management attention has focussed more on production and quality than on safety, health and related loss potential sources. As a result , occupational safety and health activism has grown, government legislation of compensation and occupational safety and health standards have progressively developed and stronger liability attitudes have been taken by courts of law.To improve efficiency and allow development in more competitive markets, rising labour costs, equipment costs and safety related financial losses have dictated that attention be given to conservation of all resources. Conservation of resources, people, equipment, material and environment, can no longer be addressed in isolation but must be managed integrally with production and quality. To this end, systems have developed utilizing sound management principles applied with equal intensity to production, quality and loss potential"

Jan 1, 1987

By R. R. Klimpel

"SYNOPSISA discussion of the importance of flotation rate in the analysis of mineral flotation is presented. In particular, the highly interactive nature of the flotation ""system"" is emphasized where there are components of chemistry, equipment, and operating conditions simultaneously involved. It is further shown that: 1) flotation rate must be measured in order to economically optimize the performance of an industrial flotation circuit, 2) that consistent patterns exist in both flotation rate and equilibrium recovery when changing various settings of the system components, 3) that knowledge of these patterns is necessary in order to avoid making system changes that are either self-compensating or dramatically re-enforcing in some particular aspect of performance, and 4) the rate related role of the chemistry component (e.g.frothers and collectors) is often much bigger than is sometimes realized (especially in a negative sense involving overdosing of reagents). INTRODUCTIONFroth flotation is widely usedl-6 in mineral beneficiation processes as a method for separating different types of finely divided solids present in a liquid (usually aqueous) suspension. The approach is based on the contacting of solids with upward moving air bubbles in an agitated vessel where the solids are exposed to chemicals (collectors) which create a condition favoring the attachment of a certain portion of the solids to the air bubbles. This selected portion is then removed in a froth stabilized by chemicals (frothers) and subsequently recovered from the flotation vessel. Depending on the settings of the various components of the flotation ""system"" (see Figure 1) it is possible to achieve a wide range of flotation performance."

Jan 1, 1984

By G. Winkel

Safety conditions in industry have greatly improved over time. However, around the world, in Canada, and in each province or territory, people are still the victims of serious industrial accidents. The increasing safety of people at work then continues to be an imperative in industry today.<p> So how do we achieve a workplace where no one gets hurt? Well, in simple terms, folks need to be protected from unplanned exposures to equipment or energy sources that can do harm. If you think about it, all of our efforts in loss management and safety should then be directed toward avoiding these uncontrolled events. And it works! Our safety performance over the years has enjoyed tremendous improvement due to this support for loss management and safety. We now explore best practices toward achieving that next step in safety improvement.<p> As shown following, a large combination of loss management activities act together to support safety performance. Many of these activities are interrelated and some people have described them as the ?inputs? into an approach or program for achieving safety. Using this description, it follows that the ?outputs? of the program are some of the advertised measures of safety we see around us today, such as injury frequency rates. <p> It is asserted that a leadership focus to regularly measure safety and loss management activites (so-called ?inputs?), as a basis for taking supportive actions to ensure their effectiveness, is the basis for safety results (so-called ?outputs?) that consistently achieve high standards of excellence.<p> The concept of managing input activities, as enabled by effective measurements, can significantly act to transform our focus and priorities in the workplace. Supporting input activities like strategies, plans, or procedures with our best efforts will get us to our intended goals. Tracking outputs alone will not.<p> Safety and production have traditionally been cast as competing objectives. When both objectives are mutually supported and considered, however, people will invent ways of doing work that support both safety and production, and any other business parameter. When done right, innovation through meaningful involvement of affected people in the workplace will support safety excellence in a manner that in turn improves business efficiency overall.<p> For a workplace to be safe, it then requires everyone?s help and participation to make it happen, a collaborative effort by management, leaders, and frontline folks with the power and responsibility to take appropriate action at every level in the organization. In this way, everyone becomes a leader in safety.<p> The achievement of commitment to loss management input activities by folks in the workplace is the basis for attaining safety excellence. A workplace founded on commitment supports a safety culture with a vision for safe work performance at outstanding or world-class levels of achievement.<p> One may ask if injury incidents will be eliminated with this commitment and focus on workplace safety? Well, despite our best efforts in this area, there is never a guarantee that things can?t go wrong. We are simply not perfect. There remains in our workplace complexities and unanticipated risks that can have disastrous consequences if not managed at every moment. And when it goes wrong, we need to know we?ve truly tried our best, and now we have more to learn so we can get even better. <p> That?s the challenge represented by the safety imperative, a challenge to take safety performance that next step, a fulfillment of our commitment to the moral obligation we have to each other?s safety. It?s an effort that will continually raise the bar of world-class safety performance achievement for future generations. It?s a legacy we can be proud to be part of.

Sep 1, 2004

By Christoph Broeckmann, Andrew Gardula

"The adoption of high-pressure grinding throughout the cement industry has yielded enormous savings in energy and wear material costs. There are also a number of installations, which are applied in iron ore and kimberlite processing operations. High pressure grinding offers the same potential for energy and media savings, as well as opportunities for improved, downstream metallurgical performance, in hard rock mineral processing. This paper focuses on developments in machine design and wear surface engineering for high-pressure grinding of the hard rock ores in the mineral processing industry.INTRODUCTIONIn the early eighties 3.4 % of the world electric energy was consumed for crushing and grinding operations of minerals and 0.6 % in the ore dressing industry. During that time using a laboratory press Prof. Schönert found that interparticle comminution at high pressure requires remarkably less energy as conventional grinding technologies. In grinding of cement clinker he expected energy savings between 33 and 50 % compared to ball mills [1]. Piston presses are limited in throughput. Thus, the principle of interparticle comminution was adapted by the use of high pressure grinding rolls (HPGR) to a continuous plant process. Figure 1 shows the main components of a roller press: The roller nip of width s is formed between the floating roller (1) and the fixed roller (2). The diameter of the rolls will be denoted with D, the width with B. The total press force F can be adjusted using a hydraulic system with two or four pistons (3). In order to compare machines with different roll geometries the specific pressing force p is introduced:"

Jan 1, 2005

By J. W. Spyker, D. H. Filson, W. H. W. Husband

"Large deposits of sodium sulphate exist in southern Saskatchewan in the brines or muddy crystal beds of alkali Jakes. Currently, more than 300,000 tons per year of sodium sulphate are produced from these lakes and sold as salt cake to the paper industry. Most of the production is obtained from the brines of a limited number of Jakes.The Saskatchewan Research Council was requested to develop a process for recovering sodium sulphate from the muddy crystal beds so that this type of deposit could be exploited in the future. A flowsheet was developed with the aid of phase diagram data and the process was studied on a pilot-plant scale using raw material from three different lakes. Satisfactory yields and product purities were obtained in all cases, and an economic analysis indicated that a 100,000-ton-per-year sodium sulphate plant could produce salt cake at a cost of $12.26 per ton for a rate of return upon investment of 16 per cent at current market prices."

Jan 1, 1966

By W. P. Tassie

"The location of Quintette Coal Limited&apos;s pit and geologic nature of the dedicated reserves combine to introduce a number of factors which can adversely affect waste dump stability. These factors include steep terrain, variable material type and particle size, and precipitation. This paper describes the solutions to related waste dump problems. A brief geotechnical review of the waste dumps is given and Quintette&apos;s operational strategies during periods of dump stability and instability are discussed. Despite best efforts, failures occasionally occur and discussion is included on Quintette&apos;s success at bringing failed dumps safely back into use. IntroductionQuintette Coal Limited (QCL) property is situated on the east slope of the Rocky Mountains near Tumbler Ridge, approximately 120 km southwest of Dawson Creek, British Columbia. This surface mine is located on mountainous terrain and is subject to climatic extremes of wind, precipitation and temperature.QCL has a current annual production of 4.75 million tonnes of metallurgical coal with a stripping ratio of 7: 1. This correctly implies the extraction of over 33 million bank cubic metres (BCM) of waste which is placed on numerous waste dumps at various locations adjacent to the pit.There are three active pits - Mesa, Wolverine, and Shikano (Fig. 1). Shikano is a newly developed pit located near the plant site. It is not subject to the unique dump management problems prevalent at the Mesa and Wolverine pits, therefore the Shikano waste dumps will not be discussed . The dumps for the Mesa and Wolverine pits, however, have been technically and operationally challenging since shortly after mining began in 1983. Their characteristics, associated site specifics and management, therefore, are the subject of this paper.Waste dump locations for the Mesa and Wolverine pits are shown in Figures 2 and 3 as is the relative waste distribution . Each sub-pit is connected to a principal waste dump in reasonable proximity and to an alternate dump should disposal of waste be necessary at that location. The waste dumps are constructed from the top elevations initially to coincide with subpit development. In the initial years (1-7) waste dump heights will be up to 250 m, then, as the mine matures (8-20 years), waste dump maximum heights will continuously decrease to coincide with lower bench elevations"

Jan 1, 1988

By Kyle Selga, Christopher J. Greet

"The Pulp Chemistry Monitor (PCM) has been installed and operated in a number of concentrators in Australasia, and has produced some very interesting results. PCM measures the pH, Eh, dissolved oxygen, temperature and oxygen demand of process streams within a concentrator continuously and in real time.In the example presented in the paper the cleaner feed pulp chemistry is measured, and related back to changes in the mineralogy as well as variations in metallurgical response. For example, a decrease in Eh and dissolved oxygen as well as an increase in the oxygen demand. These changes in the pulp chemistry appear to coincide with increases in the feed grades, probably higher pyrite grades. Further, these variations in pulp chemistry and feed mineralogy have a negative impact on the concentrate grade and recovery.The implication is that if the pulp chemistry is monitored it is possible to predict changes in the mineralogy of the system, and from this the metallurgical response. Further, the changes in pulp chemistry can be used in a control system to counter the changes in mineralogy and maintain the metallurgy.IntroductionIt has long been recognized at a fundamental level that the flotation behaviour of sulphide minerals is dependent on the pH and Eh of the system (for example: Tolun and Kitchener, 1964; Woods, 1976). However, measuring pulp chemical parameters within an operating concentrator has had limited attention. Woodcock and Jones (1970a and b) were among the first to actually collect data from operating plants. Jones and Woodcock (1984) identified some of the chemical complexities of flotation pulps, and noted that most concentrators already operate at high levels of metallurgical performance but there was still considerable scope for improvement. These gains would, in part come from more effective chemical control. In the same volume, Healy (1984) discussed metal ion hydrolysis and precipitation, redox chemistry and how the surface chemistry of sulphide minerals can be influence flotation behaviour. The impact of grinding environment on the pulp chemistry and flotation response of a complex polymetallic sulphide ore is discussed by Forssberg and Subrahmanyam (1993). Their work essentially contrasts the pulp chemical and flotation performance of pulps ground with conventional ferrous grinding media to a fully autogenous system. The data suggested that the reduction or removal of iron hydrolysis contamination from the system could have a positive influence on flotation behaviour, and perhaps the first stage of “controlling” the chemistry of the system should be in the grinding circuit. Grano et al (1995) demonstrated that the collection of pulp, solution and surface chemical data could identify weaknesses within a concentrator, and from these data develop, test and implement solutions that improved the process. Greet et al (2006) showed that the pulp chemical trends observed through primary grinding and rougher flotation circuits of most sulphide flotation concentrators are approximately the same. There are differences in the magnitude of various pulp chemical parameters (pH, Eh, dissolved oxygen, temperature and oxygen demand) as a result of variations in the feed mineralogy and processes employed. Further, it was noted the Eh shifted to more reducing values of the ten days measurements were collected, and this change could be traced to an increase in the iron sulphide content of the feed. Metallurgically, this resulted in an increase in nickel recovery through the recovery of nickeliferous iron sulphides, and a decrease in nickel concentrate grade."

Jan 1, 2016

By Murray Pearson, Jack Murray

"The danger of autoclaves lies in the high temperatures and pressures that exist in autoclave vessels. The usage of autoclaves will continue to expand in the mining industry because of their efficiency and environmental friendliness. But increasing attention must be paid to ensuring their safety. Safety Instrumented Systems (SISs) play a critical role in autoclave plants by detecting potentially dangerous conditions, taking the plant to a safe state, informing the operator about the plant status and the cause of the trip and expediting safe plant restart. The SIS should ideally be fully integrated with but functionally independent of the Basic Process Control System (BPCS) and provide redundant logic solvers to increase safety and plant availability while reducing spurious trips.INTRODUCTIONWikipedia defines an autoclave as follows: “An autoclave is a pressurized device invented by Charles Chamberland in 1879 designed to heat aqueous solutions above their boiling point to process materials.” A typical autoclave system used in the metallurgical industry includes, besides the autoclave vessel, heat recovery (heater) vessels, high pressure positive displacement (HPPD) feed pumps, vessel lining systems, specialized internals and components, agitators, pressure letdown or flash vessels, isolation and control valves, over 2,000 I/O points and related instrumentation, and emergency relief systems."

Jan 1, 2009

By D. A. Ainsworth

"The first known use of activated carbon dates back to the Ancient Egyptians who utilized its adsorbent properties for purifying oils and medicinal purposes. Centuries later, the early ocean going vessels stored drinking water in wooden barrels, the inside of which had been charred. (However, by modern definition the carbon used in these applications could not truly be described as activated.) By the early 19th century, both wood and bone charcoal was in large scale use for the decolorization and purification of cane sugar.However, it was not until the beginning of the First World War that the potential of activated carbon was really capitalized upon. The advent of gas warfare necessitated the development of suitable respiratory devices for personnel protection. Granular activated carbon was used to this end as, indeed, it still is today.By the late 1930's there was considerable industrial scale use of carbon for both gaseous and liquid phase application and new manufacturing processes had been developed to satisfy the needs of industry. During the 1939-1945 war, a further significant development took place - the production of more sophisticated chemically impregnated carbon for the removal of both war and nerve gases."

Jan 1, 1984

By Allen Chung, John Twomey, Christopher J. Greet

"It is widely accepted that the type of grinding media has an impact on the grinding chemistry and subsequent flotation behaviour of the sulphide minerals being separated. There are countless laboratory investigations demonstrating that inert grinding media produces more oxidising pulp potentials, reduced levels of grinding media corrosion products and superior concentrate grades and valuable metal recoveries. However, taking these results to industrial scale has proven difficult.Work conducted at the Ernest Henry Mine, in north western Queensland, Australia, at laboratory and pilot plant scale clearly indicated that using a high chrome grinding media resulted in significant improvements in both copper and gold recoveries. However, advancing this work to plant trial represented considerable financial and technical risk to the mine.This paper provides details of the protocol developed and used during the high chrome grinding media plant trial. It describes the test regime employed to measure changes in pulp chemistry, and the statistical methodology utilised to interpret the results. The work also highlighted the need for close cooperation between the metallurgists on site and the researchers conducting the trial.To date, the trial has produced excellent results: indicating that the copper recovery has improved by about 2 percent. The successful application of high chrome grinding media to the Ernest Henry ore has increased metal value by $18.7 million USD per annum based on current spot price for copper.INTRODUCTIONTheoryThe application of electrochemically inert grinding media to mineral systems has been extensively studied (Table 1). Broadly, these studies indicate that most sulphide minerals are more noble than the grinding media used during comminution. Therefore, the sulphide minerals are cathodic with respect to the forged steel grinding media, and the following reactions apply:"

Jan 1, 2011

By J. M. Cummings

CONSIPERABLE information on the industrial or non-metallic mineral resources of British Columbia has been published. For a general resume of the subject, reference may be made to a paper presented by A. M. Richmond before the Annual General Meeting of the Institute in 1935 (1). To avoid duplication, the present paper is confined to a discussion of the existing industrial mineral industry of the Province and of the factors governing its present and future development. British Columbia&apos;s mineral production in 1936 had a value approximately 15 per cent of that for the whole of Canada. Preliminary estimates for 1937 indicate that this proportion has been maintained, although the totals have increased about 25 per cent. The following table presents comparative figures, for the year 1936, illustrating the relative importance of the major divisions of the mineral industry in British Columbia and in Canada as a whole.

Jan 1, 1938

By C. S. Parsons

Introduction Up to the present, the operation of small mills for the treatment of gold ores has not been favoured in Canada to the extent that it has in other countries. For instance, a list of the operating properties in Southern Rhodesia, published in The Rhodesian Mining Journal of November, 1934, shows for the month of September, 1934, that there were over 500 small mills treating less than 50 tons per day, and the majority of these between 5 and 25 tons. They are operated by individuals, syndicates, and small mining companies. It is presumed that the operations are profitable, although from the published figures of the tonnages treated and the yields, it is difficult for one familiar with Canadian operations to understand how this can be possible, in the majority of cases. Most of these small mills employ stamps with plate amalgamation and with, occasionally, tables to produce a concentrate. Enquiries have been received from many parts of the world respecting milling practice suitable for small gold mines and the type of plant used in Canada. The tenor of these enquiries leaves the impression that the majority of the writers assume that the practice would be similar at all small properties. This, of course, is not the case. Conditions vary widely, and what would be a suitable mill for a typical Nova Scotia ore would not necessarily be wholly adaptable to many ores in Ontario, Quebec, or British Columbia. This paper has been written with the intention of inviting discussion, and it is hoped that, by such discussion, the subject will be more fully dealt with than has been possible in the time at the disposal of the writer. Only more or less standard principles and practices have been dealt with, and, purposely, no reference has been made to plants using mills of the Hadsel, the Nutt, or the Gibson type. As there is available but little reliable information on the costs of installation and operation of small mills, it is also hoped that those contributing to the discussion of milling practices for small mines will be in a position to give these data for the benefit of those contemplating the erection of small plants in Canada. Although it is difficult to generalize, it can be said that there are three types of gold mills commonly used at small mines: (1) Amalgamation and Gravity Concentration; (2) Amalgamation and Flotation; and (3) Cyanidation.

Jan 1, 1935

By J. F. Jackson, R. W. Mau

"The first commercial installation in the mineral industry of the ""Verti-Press"" pressure filter was made by Falconbridge Limited at the Strathcona Concentrator to filter copper concentrate. The filtercake produced contains 6 - 7% H2O, an improvement from the 12 - 13% H2O produced by an internal drum filter, at rates of up to 20 t/hr. A novel slurry feed system incorporates a hose pump and a pressurized slurry accumulator.INTRODUCTIONIncreased copper production from Falconbridge Limited operational mines in the Sudbury Area has exceeded the current refinery capacity. A copper concentrate has been produced to overcome this constraint and has been shipped to custom smelters either as a slurry or as a 12 - 13% moisture filtercake utilizing an internal drum filter.With the treatment of the new Deep Copper Zone from the Strathcona Mine, copper concentrate production was forecast in excess of the installed dewatering capacity. The filtercake was too wet to transport by truck and the custom smelter refused to handle this product at the truck unloading site. The filtercake had to be trucked to a rail spur and transloaded into gondola cars. This system was expensive, incurred unaccountable losses and the concentrate was assessed a moisture penalty.To reduce the concentrate moisture content to permit direct shipment by truck, two basic systems were available; vacuum filter followed by a thermal dryer or a pressure filter. Past experience with the high capital and operating costs of dryers led Falconbridge to closely examine the pressure filter alternative.COPPER CONCENTRATE PRODUCTIONThere are two separate circuits at the Strathcona Mill; one treating nickel ore and the other treating copper ore.The rougher concentrates produced by both circuits are conditioned with lime and cyanide before the copper-nickel separation in a flotation columns. The concentrate consisting of cha lcopyrite with mi nor cubanite is very clean as shown in Table I. Currently 50% of the copper in the plant feed reports as copper concentrate, in the past, this has been as high as 70%."

Jan 1, 1990

By Tim Edwards, Richard Triglavcanin, Ian Arbuthnot, Darren Colwell, Brad Garraway, Ken Roberts

"In the mineral processing industries, there is an increasing need to design thickeners which are able to produce high density underflows usually referred to as “paste”.The behaviour of a flocculated suspension in compression needs to be well understood in order to arrive at a reliable thickener tank configuration (i.e. diameter, cone angle and depth) for a required paste result.As a suspension approaches paste consistency, it’s fluid characteristics change markedly. It develops a high yield stress, and may have an increased tendency to form agglomerates, which lead to a phenomenon known as “rotating beds”, “donuts”, or “islands”. These characteristics present challenges to the designer of the rake mechanism.The subject paper addresses the requirements for designing a paste thickener, covering the following topics:o Testwork for thickener sizingo Design of rake mechanismso Suspension rheology and effect on designo Case studiesTESTWORK AND SIZING FOR PASTE THICKENERSThickening slurries to the maximum possible density (paste) is becoming increasingly common. Applications such as Autoclave feed thickeners, paste backfill and some counter current washing (CCD) circuits are all examples of potential paste thickening applications. The principle of paste thickeners is that the compression zone is much deeper than on either high rate (HRT) or high compression (HCT) units; generally 3 metres or more. As the compression zone gets deeper, theunderflow density for a given flux rate (tph/m2) increases, as a result of two factors:1. Longer bed settling time. Settling flocs move relative to one another and release interstitial fluid when they are in compression. Increasing bed residence time achieves higher density underflow as more fluid is removed.2. The nett weight of the bed creates a compressive force on the settling flocs. This force increases with depth, so that the flocs at the bottom of the bed experience the highest compressive force. This represents the driving force to expel interstitial fluid and hence increase bed density."

Jan 1, 2005

By R. S. Douglas

Introduction During the past few years, a number of changes in the mine operations at Copper Mountain have taken place. The modernization and mechanization were necessitated and given impetus by wartime and other conditions, which were: (1) The urgent need for copper for wartime purposes. (2) The scarcity of skilled labour for underground work. (3) The increase in labour and supplies cost. (4) The necessity of finding ways and means of increasing the output per man-shift, because of the scarcity of skilled labour and the rising cost of labour. (5) The desire to increase safety measures, reduce the silicosis hazard, and aid mine ventilation. (6) The desire to improve the general working conditions in the mine for all workmen. (7) The desire to reduce the amount of dilution in the ore stream by a more selective yet highly productive method of mining. To this end, mining with diamond drills, and transferring broken ore with slusher hoists, appeared to be the answer to the problem. After considerable discussion and estimation of costs for comparison with those of the operation as carried on at that time, the proposed methods were tried out and, in practice, gave very gratifying results. Reference at this point is made to the paper written by C. H. Brehaut, W. N. Taylor, H. A. Shannon, and R. S. Douglas, which was published in the September, 1945, issue of Mining Technology, by the American Institute of Mining and Metallurgical Engineers, Inc., and subsequently in commercial mining journals. Since that time some improvements have been made in undercutting an orebody - the first through experiment and practice, the second through making use of the earth&apos;s barodynamic or gravitational forces. It is the purpose of this paper to describe and discuss these later developments.

Jan 1, 1947