Search Documents

By G. C. McKerrow

"Mr. G.C. McKerrow, Assistant Manager of Noranda Mines and formerly Smelter Superintendent attended the meeting to answer questions as to why smelters imposed penalties for too much zinc in a copper concentrate or too much copper in a zinc concentrate, etc.D.W. Bridges -Mattagami Lake MinesWhat limits do you set on zinc and lead in a copper concentrate?G.C. McKerrow - At Noranda, we allow 5% zinc free and charge 25 cents for every unit above that. For lead, it is 1% free and 25 cents per unit above that. Lead is a much more harmful impurity than zinc because it tends to recycle more in the smelter circuit and creates a greater health hazard in the plant.E. Thornton - Sullivan GroupWHat harm does fluorine do in the smelting process?G.C. McKerrow - Fluorine usually does not occur in harmful concentrations in non-ferrous smelters. Fluorides are present in exhaust gases in the aluminum and phosphate industries. If these fumes escape into the atmosphere, they may settle out on forage grasses in concentrations that are harmful to livestock.Thorton - Sullivan GroupI have asked this question other places and have been told that it is hard on brick linings and causes gold and silver to be lost up the stack.G.C. McKerrow - Almost any volatile constituent in a smelter charge will aid in carrying other metal values. To this extent it may be harmful.E. Thornton - Sullivan GroupMr. Tait mentioned before a smelter where they have a copper-tin ore and they pay for copper, tin, bismuth and silver but object strongly to indium in the concentrate. Why would this be?G.G. McKerrow - 1 can't see why indium would be a serious impurity. It does tend to concentrate in flu dusts and if you get enough of it you can recover it and sell it but I have never heard of anyone putting a penalty on it.Question - I once ran into a small copper mine in Peru that had cadmium in the copper concentrate but no zinc. The copper smelter charged a penalty for the cadmium. Why would this be?"

Jan 1, 1971

By L. W. Hamel

"DUST CONTROL - GRANISLE COPPER LIMITEDINTRODUCTIONGranisle. Copper Limited is located in the north-central region of the Province of British Columbia, approximately 200 road miles north-west of Prince George. Mill startup was in November, 1966, at a rate of 5,000 tons per day, expanded to 13,000 in 1973. The primary crushing rate is 1,200 tons per operating hour, and the secondary 750, and they can be operated jointly or separately.DUST COLLECTION SYSTEMS There are seven dust collection systems ventilating the crushing and grinding complex. The individual pickup points are depicted on Figure 1 -""Crushing Plant Flowsheet"", and Figure 2 - ""Concentrator Flowsheet"", e.g. 1A, 1B, 3C, etc.System No. 1 - Primary Crusher The feed rock box of the Allis-Chalmers superior 42-65 primary crusher is ventilated by 19,000 CFM of air exhausted directly to atmosphere by a Sturtevant 426 M fixed discharge fan.No. Dust Pick Up Point CFM lA Crusher Feed Rock Box 19,000System No. 2 - Primary Crushing and Screening System No. 2 ventilates the primary crushing and screening equipment. A total of 19,000 CFM of air is exhausted by a Sturtevant 426 M fixed discharge fan through a Howden Type S - size 75 cyclone locally modified for wet scrubbing."

Jan 1, 1976

By B. V. Knelson

"GENTLEMEN:This paper will deal with centrifugal separation - theory and practical, and since the Knelson Concentrator is the only centrifugal concentrator with a properly fluidized bed, this paper will cover the Knelson Concentrator and its technical and structural advances over the last five years. As I am the person with the most experience in this line, I guess I am some kind of an expert; what kind I’m not sure, but some kind.This type of concentrator truly was developed because I’m lazy and I constantly look for easier ways to do things. My experience in the mining industry was very limited but I did realize in looking at placer operations, which is the application where I spring from, that it was tremendously labour intensive and my first reaction that ""my god, there must be some method or way-of handling product in a more efficient (and you can read that as being able to quickly recover very fine particle gold) way than was being shown at that time"". So, the Knelson Concentrator was born - about 6 or 7 years later. Our first attempt was a cone with about the same degree of slope as our present machine and since we had no knowledge of vibration dampening and centrifugal forces at that point, it was just an idea that this should work.Our first run was one of twenty minute duration. We did make that first machine variable speed by a mechanical belt system and we found that at about 240 rpms we were virtually shaking the gravel plant apart that we were attached to. So the first run was twenty minutes and back to the drawing board. However, that first run produced a concentrate so superior to anything we had seen previously, that we knew without any question, we were definately and accurately on the right track."

Jan 1, 1985

By P. V. Avotins, I. Djurkovic, D. R. Nagaraj, M. Grunjic, A. Day

"As part of a major reconstruction and expansion of the Majdanpek Copper Mine, an investigation and optimization of the flotation collector regime was undertaken. The flotation response of the major minerals to various reagents and the effect of pulp chemistry was studied from both a fundamental and practical point of view. These studies led to plant trials and the eventual adoption of a modified collector suite which improved both copper and gold recoveries.INTRODUCTIONThe Majdanpek Copper Mine processes 40,000 tons per day of ore containing about 0.43% cu. In addition to copper, the ore also contains recoverable quantities of molybdenite and gold. The mine has been in operation since 1961 and is the largest in Yugoslavia. It is currently undergoing major reconstruction and expansion. The flowsheet of the Majdanpek concentrator is shown on Figure 1.The ore body is variable in composition and changes in mill feed require proper control of operating variables to achieve the optimum metallurgical results. A detailed study including grindability, flotation response, and solid-liquid separation was carried out on several samples of the ore. Flotation response and the choice of reagent chemistry were found to be very important in achieving the highest recoveries of metal values. An automatic reagent control scheme insured that optimum dosages were used in the plant.The flotation collectors used at the present time include sodium isopropyl xanthate (SIPX), AERO 3302 Promoter and AERO 5415 Promoter. The addition of AERO 5415 to the reagent suite is a recent development and was based on the favorable results obtained in the extensive laboratory testing program conducted to establish the optimum reagent combination and dosages. Subsequent plant tests confirmed that AERO 5415 provided significant improvements in copper and gold recoveries. A description of the mineralogy of the Majdanpek ore and details of laboratory and plant metallurgical data are given in this paper. The chemistry of AERO 5415 Promoter and its interaction with minerals relevant to Majdanpek ore are also discussed."

Jan 1, 1992

By P. G. Claridge, R. A. Tenbergen

"Pipe Open Pit ore is delivered by rail to the Thompson Mill at a rate of 34,000 tons per week. Ore is milled at a rate of 220 tons per hour.Characteristics of the serpentinised peridotite host rock are such that significant deviations from hitherto experienced milling practice became a necessity because of coagulation of the gangue upon cominution.Extensive development work was done in the grinding and classification circuits to better understand the ore characteristics and optimize operating parameters and the use of available equipment. This work ultimately resulted in the change from 30 to 20-inch diameter cyclones.Coagulation of the ore slurry and the characterstics of the sulfide minerals necessitated an ""unconventional approach"" in processing as compared with the beneficiation of Thompson Mine ore.Recent changes in ore characteristics led to testing of antistatic agents to reduce tailing losses."

Jan 1, 1975

"The outlook for Eastern Canada is decreasing coal production over the next few years; however, a reappraisal of the long-term requirements and increased prices of coal could lead to a revitalizing of the industry. The market for Western coal is expanding and is expected to exceed 50 million tons per year in the metallurgical and thermal power fields. Western coal reserves are currently estimated at 119 billion tons. Technical developments in Eastern Canada include a shearer and gate-end support system to mechanically cut the stall and brushing at the tail-end of a longwall. In Western Canada, the most modern equipment is used in mining, beneficiating and shipping coal. Results to date on the underground hydraulic experiments exceed expectations. The importance of reclamation is recognized and plans have been made to restore and re-vegetate disturbed areas and mine dumps. In Eastern Canada, experiments were started to determine the feasibility of coal reclamation from mine dumps, including one dump that is on fire. The Mining Research Centre, Mines Branch, continued to conduct research work oriented toward solving Canadian mining problems The Western office of the Centre, opened in 1970, was set up primarily to study problems associated with a resurgent coal industry."

Jan 1, 1971

By A. McLean, M. Barati

In this paper, examples are presented of pyrometallurgical research and associated teaching activities during the past century within the Department of Metallurgical Engineering, now the Department of Materials Science and Engineering, at the University of Toronto. Throughout these years, pyrometallurgical research has been characterized by recognition of the importance of the interdependence of measurements and models as well as the development and application of sensors, for the generation, validation and practical implementation of new knowledge. The important role played in the delivery of lectures and participation in joint research by Adjunct Professors with strong backgrounds in the pyrometallurgical industry is described. Projects conducted in close collaboration with the industrial sector and opportunities for students to obtain practical experience working as teams on a "round-the clock" shift basis within an industrial pilot plant environment are outlined. These activities, together with the involvement of students in poster competitions and the presentation of papers at society conferences and technical meetings, are still vital elements in the development of pyrometallurgists equipped with the appropriate professional skills for subsequent employment within academia, government laboratories or the industrial sector.

Jan 1, 2015

By Corrie Pitzer

Safety performance in many companies and even industries has stalled in the few years. Accidents rates are at a ?plateau? and yet, serious accidents and fatality rates are not. In more dramatic cases, such as in the BP Texas disaster, organizations that have ?exemplary? safety statistics, suddenly have a catastrophic or multi-fatality event occurring. Other classic examples are the Piper Alpha disaster and NASA?s Challenger and Columbia disasters and even the Chernobyl nuclear reactor. Looking into the root causes of these accidents provides an insight into the events and deficiencies that led up to the accident, but what are the common features in the organization?s mindset? What characterizes these organizations? decision making, their approach to safety and to risk and are there specific cultural features that can be delineated? The research and review presented in this paper covers a period since 1994, which started in the Australian resource industry and since then covered international events. The features of these organizations are summarized as the seven deadly delusions, based on extensive research since 1997 of organizations that suffered unexpected disasters. Their huge focus on safety, the achievement of lofty goals and celebration of safety successes led to ?mindset? that they are leaders in safety, protected by an extraordinary safety system and that their safety incident figures indicated a truly world-class safety performance. It led them into the trap of the seven deadly delusions?

May 1, 2011

By Marcel Vallee, Fernand Dubuc

"The St-Honoré carbonatite complex, located 8 miles north of Chicoutimi, Quebec, was discovered in September 1967 as abnormal radioactivity was detected in the course of SOQUEM's aerial surveys. The complex, covered by a shallow layer of Trenton limestone, has been explored by aeromagnetic, ground gravimetric and magnetic surveys, and 12,013 feet of diamond drilling. Its age, from potassium-argon dating, is 650 million years. The carbonatite is approximately kidney-shaped and has a surface area of 6 square miles, 20 per cent of which is explored. It shows a central core of coarse-grained massive dolomitic carbonatite and an outer ring of foliated dolomitic carbonatite.The exploration work to date has resulted in the discovery, in the foliated carbonatite, of an incompletely drilled niobium (columbium) zone of pyrochlore-bearing carbonatite, at least 1,000 by 800 feet in size. This zone contains 5,000 tons per vertical foot grading 0.86 per cent Nb205 or at least 15,000 tons per vertical foot grading 0.66 per cent Nb205 or 45,000 tons grading 0.48 per cent Nb20s. The pyrochlore contains an average of 64 per cent Nb,Os. The central core contains a zone of rare-earth-bearing carbonatite (as monazite), grading up to 4.5 per cent rare-earth oxide, 3,500 ppm zinc and 290 ppm molybdenum. Stocks of nepheline syenite and magnetite diorite accompany the carbonatite. The total analysis and trace-element contents of typical rocks are presented."

Jan 1, 1970

By Tom Cooney

A small number of mining contractors worldwide have evolved their businesses to be able to provide a ?total service solution? to their clients. Thiess, an Australian-based international mining service provider, works with numerous clients to tailor delivery methods and commercial arrangements to suit individual projects. The benefits of Thiess? extensive experience is brought to each client and project, whilst business improvement within projects, to the mutual benefit of both the client and Thiess, is a key part of all long term contract relationships. Historically, optimal business outcomes were closely related to the achievement of production and cost performance measures. Whilst these remain fundamental to successful mining businesses, other elements of sustainability are assuming increasing importance. As a large energy user, greenhouse and energy management is becoming an important part of Thiess? business. Thiess is a signatory to Australian government initiatives such as Greenhouse Challenge Plus, and is integrating energy management into its operations and business improvement programs, in many cases to the benefit also of the client. This paper will highlight the benefits that an organisation such as Thiess can bring to a mine owner. Thiess? approach to business improvement and cost reduction, sustainability and energy management, as well as the relationship between these will also be considered. Increasingly, overall mining performance is dependent on the alignment of formally disparate elements.

May 1, 2007

By J. S. Stickling, P. J. Whittaker, N. O. Lotter

"Assessment of opportunities to improve mineral processing performance in existing concentrators and in describing undeveloped orebodies is key to improving the business case of a mining company. This assessment has traditionally been performed using the distinct and separate inputs from mineral processing and mineral science.More recently, process mineralogy has been used to integrate these two disciplines. This trend has been driven by the need to develop and process more challenging ore deposits, and has been assisted by the availability of modern automated instruments. Together with the acquisition of a QemSCAN (quantitative evaluation of materials by scanning electron microscope) from CSIRO in Australia, and with the use of a supporting SEM with EDX/WDX capabilities and an XRD, the development of process mineralogy at Falconbridge commenced in 1997.The sampling challenges in presenting a QemSCAN with representative sample material at the polished section level are significant, but have been effectively addressed. The full description of this aspect is beyond the scope of this paper.It is shown that, by use of this approach, the set nature of an orebody can be best exploited with selected flowsheet changes in a concentrator which address the generic characteristics of the orebody. In this way, the flowsheet provides a process that more effectively fits the mineral processing requirements of the ore. This leads to clear and tangible improvements in grade and recovery."

Jan 1, 2002

By V. I. Lakshmanan, D. A. Mackie

"1. INTRODUCTIONIn the past two decades, low-grade gold and silver ore bodies in the United States have been exploited by heap leaching, primarily with sodium cyanide solutions. This method has proven to be a viable alternative to conventional milling due to its low capital and operating costs. Successes have been made, particularly in Nevada, where ores are well oxidized and the climate is conducive to this method. in recent years, heap leaching has been tried in northern latitudes with some success, however, in using this method, operators face more severe limitations than do their neighbours to the south.This paper evaluates the limitations of heap leaching with particular emphasis on northern climates and introduces an alternative method to recover precious metal values in a continuous vat. This proprietory technology, known as the Mackie Vat Leaching Jig, shows promise, with improved gold recovery and potential to operate in cold climates.2. WHAT ARE THE LIMITATIONS TO HEAP LEACHING?Heap leaching of non-refractory ores is subject to the following limitations:1. Minimum amount of free gold and nuggets in the ore.?. Minerology of the ore--accessibility of gold to lixiviant.3. Minimum particle size and size distribution of crushed product to allow percolation of lixiviant through the heap.4. Minimum amount of clays or clay-like slimes that can cause coating of ore particles and channelling of lixiviant.5. Minimum strength of ore particles or agglomerations to allow economic height of heaps to be built.6. Amount and suitability of real estate.7. Amount and type of precipitation.8. Ambient temperatures.9. Possible poorer lixiviant diffusion.10. Possible lower oxygen content in dissolved cyanide solution with higher heaps, particularly with ice and snow cover."

Jan 1, 1989

By C. J. Brown

"Access to the outside world is supplied by the Alaska Highway to continental Canada and the United States, the Haines Highway, and by the White Pass & Yukon Route to Skagway and Vancouver. Communities and mining developments located along the Alaska Highway are supplied daily by truck transport with commodities originating in Whitehorse, Edmonton, and Vancouver.The average payload on the Alaska and Mayo Highway is in the order of 16 to 25 tons and is subject to government regulations. Highway haulage distances to railhead at Whitehorse vary as does the direction. The Clinton Creek asbestos development is located 395 road miles north-west of Whitehorse whereas the United Keno Hill operation is 287 miles to the north. Cassiar Asbestos is located in Northern British Columbia at a distance of 357 miles south-east of railhead at Whitehorse. In order to service these various mines multipurpose highway vehicles have been designed to allow maximum backhaul of petroleum products. The White Pass & Yukon Route was established as an integrated transportation system from 1955 when it became apparent that three non-integrated systems (ship, rail and truck), with the various paper work and rising costs, could not continue to serve the needs of Yukon. Integration became the company policy and a system was developed. A special container ship (Clifford J. Rogers) was designed and built. This was the first specially built container ship in the world. The northern container integrated system was operational in 1955.In 1965 over 8.5 million dollars were spent in upgrading the container facility and the construction of a tanker-container ship designed specifically to serve Yukon and Northern B.C. This program was based largely on experience gained with the original container concept. Two tanker-container ships handled"

Jan 1, 1973

By M. Kalin

"Ecological Engineering, a biotechnological approach to the decommissioning of base metal mining wastes, is being tested on two pits (Gloryholes) in Newfoundland, Canada. Pit #2 has an average pH of 3.5 and flows into Pit #1 where, through additional ground water contribution, the pH is circumneutral, ranging between 5.5 to 7.The AMD in Pit #2 originates from underground workings and exposed massive sulphide on the pit walls. The overflow from Pit #1 averages about 10 L/s with less than 0.2 mg/L of Cu and 40 mg/L of Zn.Ecological Engineering utilizes organic substrate as a source of carbon and nutrients for microbial populations which can generate alkalinity and reduce metals. In 1989, limnocorrals (enclosures of 4 m diameter and approx 3 m depth) were placed in both pits to test the most suitable organic amendment (peat and sawdust). Microbial alkalinitygeneration was evident 95 days after placement of the amendment on July 4, 1989. The pH had increased after 120 days from 3.5 to 4.5 and by day 480 the pH was 7 in limnocorrals in Pit #2. Zinc concentrations in the limnocorrals in Pit #2, dropped from an average of 35 mg/L to about 2 mg/L or less, by day 480.A scaled-up experiment has been under way since August 25, 1990, where 390 m3 are treated in pit #2 and 750 m3 in Pit #1. One hundred eighty days after placement of the amendment, zinc was reduced in the acid Pit #2 from 40 mg/L to 15 mg/L. Research is underway to determine those factors which limit microbial activity."

Jan 1, 1992

By K. B. Chaudhurl

The thermodynamics of the reactions taking place are examined with the aid of equilibrium diagrams for the Pb-O-S system. Based on investigations of chemical, mineralogical and differential-thermo analyses of intermediate products of different desulphuration degrees, an attempt is made to explain the mechanisms of the reactions in the smelting shaft of the KIVCET furnace. The differences between this and other direct lead smelting processes are demonstrated by these thermodynamic and kinetic considerations. Proceeding from these results, the practicability of direct lead smelting processes is discussed with reference to the composition of the primary feed materials to be processed. This comparison also considers the behaviour of minor metals, the products obtained and their characteristics in respect to further treatment. For assessing the operating costs, the over-all energy consumption is considered taking into account various price relations between electric energy and fuels/reductants. Based on the peculiarities of the various processes, an attempt is made to compare the necessary means of meeting the pollution control requirements. The paper concludes with reference to the criteria and problems involved in comparable evaluations.

Jan 1, 1978

By Harold L. Gibson, Don H. Rousell, Ian R. Jonasson

"The Sudbury Structure consists of three major components: 1) the Sudbury Basin; 2) the Sudbury Igneous Complex which surrounds the basin as an elliptical collar; and 3) an outer zone of shatter-coned and intensely brecciated footwall rocks. Although the Sudbury Event which formed the structure may be unique, the area has, in fact, been shaped by a series of tectonic, magmatic and mineralization events which can be considered in terms of two Wilson cycles of continental extension and closure. The first cycle, from 2500 to 1700 Ma, included the following events: doming (uplift of Levack Gneiss Complex); NE-SW extension (Matachewan dikes); N-S to NW-SE rifting (faults, mafic intrusions, sedimentation, and Ni-Cu-PGE and U mineralization); NW-SE extension (Nipissing diabase, and Ni-Cu-PGE, Ag, Co mineralization); and NW-SE and NE-SW closure (Penokean Orogeny, 1900 to 1700 Ma) with superimposed meteorite impact (1850 Ma, Ni-Cu- PGE, Zn-Cu-Pb deposits). The second cycle, from 1700 to 1000 Ma, included: N-S extension (alkali metasomatism, Au); N-S extension (hornblende diabase dikes along the Murray fault set); NNESSW extension (olivine diabase dikes); NE-SW extension (Fecunis Lake fault set); and NW-SE closure (Grenvillian Orogeny).The rich and diverse Ni-Cu-PGE and subordinate Zn-Pb-Cu and Au mineralization of the Sudbury region is related to endogenic and impact-triggered crustal extension and magmatism. The Sudbury Structure apparently was the site of a triple junction or hot-spot. The Sudbury ores, although located within an impact structure, are analogous in terms of age and tectonic setting to Ni-Cu-PGE and Zn-Pb-Cu ores elsewhere in the world. Meteorite impact accentuated on-going ore forming processes and magmatism at Sudbury."

Jan 1, 1997

By Fathi Habashi

"A process is proposed for the treatment of phosphate rock for the recovery of uranium and the lanthanides. The process assures the production of phosphatic fertilizers without polluting the environment with radioactive material.IntroductionWhile many processes for uranium recovery from phosphoric acid produced by the H2S04 route are known and utilised commercially, little is known about uranium recovery from phosphoric acid produced by the HN03 route1. Advantages of the latter route are both the elimination of the gypsum disposal problem, and the possibility of radium disposal in a controlled way2. Further, the lanthanides originally present in the rock can be recovered if the nitric acid route is used; they will be mostly lost in the gypsum produced by the sulphuric acid route3. In the present work a scheme for the recovery of uranium and the lanthanides from phosphate rock without interfering with the normal route for fertiliser production is proposed using HN03 as a leaching agent. Attention was also given to uranium decay products and their separation so that they might not contaminate the fertiliser4. Further, an attempt was made to defluorinate the leach solution in order to upgrade the fertiliser and at the same time recover the fluorine5. Rapid analytical methods for the determination of uranium, radium, and lanthanides in phosphate rock were developed6,7."

Jan 1, 1997

By Harold L. Gibson, Don H. Rousell, Ian R. Jonasson

"Abstract - The Sudbury Structure consists of three major components: 1) the Sudbury Basin; 2) the Sudbury Igneous Complex which surrounds the basin as an elliptical collar; and 3) an outer zone of shatter-coned and intensely brecciated footwall rocks. Although the Sudbury Event which formed the structure may be unique, the area has, in fact, been shaped by a series of tectonic, magmatic and mineralization events which can be considered in terms of two Wilson cycles of continental extension and closure. The first cycle, from 2500 to 1700 Ma, included the following events: doming (uplift of Levack Gneiss Complex); NE-SW extension (Matachewan dikes); N-S to NW-SE rifting (faults, mafic intrusions, sedimentation, and Ni-Cu-PGE and U mineralization); NW-SE extension (Nipissing diabase, and Ni-Cu-PGE, Ag, Co mineralization); and NW-SE and NE-SW closure (Penokean Orogeny, 1900 to 1700 Ma) with superimposed meteorite impact (1850 Ma, Ni-Cu- PGE, Zn-Cu-Pb deposits). The second cycle, from 1700 to 1000 Ma, included: N-S extension (alkali metasomatism, Au); N-S extension (hornblende diabase dikes along the Murray fault set); NNESSW extension (olivine diabase dikes); NE-SW extension (Fecunis Lake fault set); and NW-SE closure (Grenvillian Orogeny).The rich and diverse Ni-Cu-PGE and subordinate Zn-Pb-Cu and Au mineralization of the Sudbury region is related to endogenic and impact-triggered crustal extension and magmatism. The Sudbury Structure apparently was the site of a triple junction or hot-spot. The Sudbury ores, although located within an impact structure, are analogous in terms of age and tectonic setting to Ni-Cu-PGE and Zn-Pb-Cu ores elsewhere in the world. Meteorite impact accentuated on-going ore forming processes and magmatism at Sudbury."

Jan 1, 1997

By R. E. Jones

"Crusher sizing and application in mining operations is the selection of a crusher or a series of crushers to reduce run of mine ore to a size suitable for either autogenous or conventional grinding. It is important that the crusher or crushers be sized to operate within the range to which they have been designed. By the range to which they have been designed, we mean that the reduction ration must be held between specified limits. Reduction ration is the relationship between feed size to product size.In todays plants reduction is usually accomplished in three stages by primary, secondary and tertiary crushers.Primary crushers are either jaw or gyratory and are designed to handle run of mine feed at an open side setting of 5-1/2” to 7”. Reduction ration should not exceed 7 to 1.Jaw CrushersThe model size of a jaw crusher signifies the feed opening. A model 60 x48 jaw has a feed opening 60” wide by 48” long. The 48” is the dimension between the top of the swing jaw and the top of the stationary jaw. The 60” is the width between the two side frames. The crusher open side setting is the discharge opening at the bottom of the crushing chamber with the jaws in an open position. When corrugated jaw plates are used, the open side setting is measured from tip of one jaw plate to the valley of the opposite jaw plate. If a jaw crusher has a 6” open side setting with a 1” jaw motion, you could also say it has a 5” closed side setting."

Jan 1, 1974

By E. W. Johnson

"The title of my paper is ""I 'Wonder Where The Yellow Went"". As you can readily guess, it is not related to an old-fashioned ""Pepsodent"" sales pitch! Rather, it concerns a situation which arises all too frequently in some gold milling operations, namely when actual ounces of gold production do not come up to estimated or projected ounces. The boss man scratches his head and wonders where the missing gold has gone and how it has disappeared. The problem, if one exists, is amplified if one forgets that an estimate is just that - an estimate - and not a hard fact - even though the numbers are produced by computers. And yet, from the point of view of engineering; financial and production planning and security; it is most desirable to tie together all data relating to production estimates, losses and actual production.In the course of this paper reference will be made to the term ""variance psychology"", to a few of the physical properties of gold and to the nature of its occurrence in Canadian ores, in relation to the topic under consideration. Activities which have a bearing on production estimates will be reviewed. These include: weighing, sampling, assaying, estimating residual losses and, in cyanide plants, gold precipitate production. Mention will be made of apparent, unaccounted for and unknown losses. In conclusion, I shall draw from personal experience and relate three examples of ""Where the Yellow Went''."

Jan 1, 1986