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By M. H. Moys, J. A. Finch, A. R. Laplante

"A detailed review of ball milling circuit control practices in industry has been carried out. Based on fundamental process performance objectives, a standard system for base-level control of most ball mill installations is presented. This system is simple, inexpensive, and provides the major economic benefits available from contemporary automatic control technology.Value Analysis of Grinding OperationsValue analysis (or engineering, or management), originally developed by Lawrence D. Miles of the General Electric Company (1), focuses on the identification of value (product or process worth versus cost) and provides a systematic procedure for its improvement. A recent research and development project involving the application of the principles of value engineering to grinding operations has provided a basic technoeconomic model of grinding processes (2). The functional objectives of the ball milling process and the means to achieve value based grinding circuit control originate from this study.The Need for Grinding Circuit ControlThe economic effectiveness of a process is determined by the quality or value of the product and the related processing costs. If the inputs (both the raw feed and the applied processing work) are absolutely constant, the product characteristics and the process efficiency will be determined only by the engineering design. The need for and degree of process control is therefore determined by the nature of variations or upsets in the process inputs, and the extent to which these effect product value and operating costs."

Jan 1, 1988

Safe underground mine backfilling with hydraulic fill requires efficient fill drainage and stable fill retaining walls or bulkheads. If any or both the above two requirements are not satisfied, such a backfilling operation creates unsafe conditions and may lead to backfill retaining wall failures. Mine backfill retaining wall failures are always associated with economic losses, fatalities and interruption to mine production. Mining industry wants to either reduce or eliminate these fill retaining wall failures. The fill retaining wall failures could be effectively avoided through the use of fibre reinforced shotcrete fill retaining walls and engineered drainage systems through the retaining walls. This paper presents the experience of the author in developing, implementing, and monitoring several hundred fibre reinforced shotcrete fill retaining walls at a mine in Australia with the highest safety standard. The details on the mine backfill drainage system and fibre reinforced shotcrete fill retaining wall designs are also presented.

May 1, 2007

By H. Soto, J. Jara, F. Nava

"A combination of oxidation and precipitation was used to eliminate cyanide from gold milling effluents. Preliminary laboratory work developed with both synthetic cyanide solutions and with industrial effluents indicated that ozone can easily destroy free cyanide and weakly complexed cyanide (i.e. copper and zinc cyanide). In this case the reaction is quite fast and seems to be controlled by the mass transfer of ozone to the solution. Experimental results indicate that free cyanide and weak-acid dissociable cyanide in mill effluents can be reduced to less than 1 ppm. However, the iron-cyanide complexes proved to be quite resilient to destruction with ozone and they remained in the solution even after most of the free and weakly complexed cyanide was destroyed with ozone. These results were confirmed in a pilot trial developed at the Sphinx plant in northern Quebec.To deal with the problem presented by the presence of the iron complexes two different approaches were studied: use of a combination ozone-ultraviolet light oxidation, and the precipitation of iron-ferrocyanide complexes in the residual solution after ozonation. This last method proved quite promising since reduced the total cyanide levels of industrial solutions assaying as much as 250 ppm to less than 1 ppm of total cyanide. Control of the · pH of the solution was the key to obtain the precipitation of the iron complexes. The use of iron to precipitate cyanide complexes has the advantage of being less expensive and less toxic than copper (used by the Inco process)."

Jan 1, 1992

By F. Baerhold, S. Mitterecker

"Acid recovery is an important process step in pickling and leaching processes. Pyrohydrolysis in spray roasters and fluidized beds is a well-established technology to recover hydrochloric acid, but the hydrolysis in the liquid phase is more and more considered as an alternative new process route. The characteristic features of these three processes will be discussed along with select industry trends. For example, hydrochloric acid based leaching processes for ilmenite and nickel laterite ores produce far larger volumes of waste acid streams than the steel industry. Scaling-up of the spray roasting technology to the highest possible capacity is necessary in order to become more cost effective. In addition, process routes based on ferric chloride pyrohydrolysis allow the production of super-azeotropic HCl (up to 30 wt.%). Finally, the new ECOmode concept optimizes the operation of both pickling lines and the spray roast acid recovery plant. Long term results from industrial applications show that fuel savings in the spray roaster of 25% are easily achieved without additional process steps. An attractive feature is also to upgrade existing installations to higher plant capacities.INTRODUCTION Pyrohydrolysis is the conversion of metal halides into metal oxides at elevated temperatures in the presence of water vapor. Reaction products are a hydrogen halide gas and a metal oxide. The process was originally developed and introduced into the market by ANDRITZ Ruthner in the 1960’s. It has found wide technical application in the field of acid recovery and oxide production. The introduction of this process has revolutionized pickling technology. The use of hydrochloric acid has strongly increased over the last decades, since pyrohydrolysis is available for the total recovery of waste pickle liquors from mild steel pickling, as illustrated in Figure 1.Chloride media are also used increasingly in the metallurgical industry. Oxide production processes for Mg, Co, Ni, and Al have been installed. Processes using hydrochloric acid are known for the leaching of ores as well as for the re-extraction of metals from organic solvents. In both cases the recycling of HCl is of substantial importance to achieve highly economic processes and to reduce waste."

Jan 1, 2016

By K. P. Wright

"Twenty-five years ago, there were about thirty-two gold mines operating in Canada; nine of these have been in continuous operation since then and are still operating. Three of these are part of the Dome Group. Operations of these three and of the newer mines in the Group are referred to in discussing process development over the last twenty-five years.Of the Dome Mines Group, Dome Mines Limited, Sigma Mines (Quebec) Limited, Campbell Red Lake Mines Limited, Detour Lake Mine and Kiena Gold Mines Limited, three have been in continuous operation for the last twenty-five years. Dome has operated for seventy-seven years; Sigma about to complete fifty years, and Campbell approaching forty. Overall, milling processes are virtually the same as they were twenty-five years ago. Tota1 go1d production from the three mines has hardly changed; 1960 production, 416,700 ozs. versus 411,300 in 1985. Milling costs have risen by a factor of six or seven and gold price from $35/oz. in 1960 to $322 in 1985.Basic flowsheets are relatively unchanged. Sigma is an all cyanidation mill grinding in cyanide solution; Dome operates gravity concentration and cyanidation; Campbell gravity concentration, flotation, roasting and cyanidation. All three use Merrill-Crowe zinc precipitation.Detour and Kiena are two examples of the major change in gold processing in the last twenty-five years - carbon-in-pulp. This process has brought along with it other changes, such as, carbon stripping and reactivation, electrowinning, and induction furnace melting. Modern mill design with its use of outside thickeners and agitators, bulk handling of reagents, instrumentation, etc., has made a radical change in operating conditions and appearance of the new plants."

Jan 1, 1987

By Harry Siewert

"The commissioning of the 4th concentrator (C4) at Freeport Indonesia in early 1998 increased total mill throughput from 130k to 230k tonnes per day. The C4 flowsheet consists of a single 38 ft diameter SAG mill, four 24 ft diameter ball mills followed by four banks of 4,500 ft3 WEMCO flotation cells.The design of the C4 rougher flotation circuit was based on the expectation that the copper and gold recoveries achieved with the 4500 ft3 flotation cells would be equivalent to or better than that achieved with the 3,000 ft3 flotation cells in the 3rd concentrator (C3) rougher circuit. This assumption was due to the fact that the C4 flotation feed size would be less than 15% +212 microns compared to the C3 rougher flotation feed size of less than 23% +212 microns. By mid 1998 it had become apparent that the C4 rougher flotation copper and gold recoveries were below those predicted.In order to determine the cause of the lower recoveries, stage by stage rougher flotation surveys were performed in all four concentrators. The results of the surveys showed that the C4 rougher flotation circuit had a lower recovery of +200 micron material than that achieved in the C 1, C2 and C3 concentrators. Through mineralogical analysis, it was determined that a majority of the copper contained in the +200 micron fractions was liberated and recoverable. This paper describes the steps taken to increase coarse particle recovery, overall plant recovery and the results achieved."

Jan 1, 2001

By Jeffrey L. Pagnutti

Train derailment can lead to loss of capital, damage to the environment, and loss of life. Machinery condition monitoring techniques can be used to develop a structural health monitoring system for railway track to detect faults at the incipient stage, before catastrophic failure occurs. This study uses vibration measurements from a novel material haulage unit to develop a decision support system for railway track maintenance. A variety of feature sets and classifiers were compared to determine the optimal configuration for fault detection. The results highlight the shortcomings and advantages of certain methods and describe the process in which the optimal result was obtained. The Parzen data descriptor paired with a refined statistical feature set performed the task of fault detection with less than five percent false positive and false negative classification error. Overall, the outcome of these experiments indicated that condition monitoring of railway systems is a promising approach for fault detection and has the potential to avoid catastrophic failure.

May 1, 2013

By P. P. Andrieux

The recovery of the Zone G crown pillar, located between the bottom of the open pit and the top of the underground workings at the Raglan Katinniq Mine in Nunavik, started in the summer of 2008 and should be completed by the end of 2009. This article describes the rock mechanics-based approach implemented to design the recovery of this valuable block of ore. The stereophotography-based ShapeMetriX3D technique was first used to provide a comprehensive assessment of the various joint sets that comprised the pillar. Then, the statistical distributions obtained for the dip, dip direction, spacing and persistence of these sets were used in conjunction with the geometry of the large-scale faults present in the area to build and run a series of explicit rigid numerical models. Each of these models had a slightly different jointing geometry, randomly constructed from these statistical distributions. Incorporating in a properly formulated numerical model the variability of some of the input parameters has allowed the engineering team to assess in a rational and reliable manner the likelihood of success of the proposed mining method and sequence.

May 1, 2009

By L. Lui, A. Cauchon, A. R. Laplante

"The gravity circuit at Les Mines Camchib Inc. consists of two pinched sluices to bleed a feed to one of two 76 cm (30"") Knelson concentrator. The Knelson concentrate is upgraded to smeltable grade with a smaller Knelson (18/30 cm) and a riffleless table. Their tails are column cyanided and washed prior to recycle to the grinding circuit. This paper details size-by-size circuit performance. The Knelsons recover around 90% of free gold (as determined by Mozley Laboratory Separator), even below 37 µm. The sluices are ineffective, with upgrading ratios around 2, but approaching unity in the fine sizes. Much of the effectiveness of the circuit lies in the high gold circulating loads in the grinding circuit, which partly atone for the poor sluice performance, and the ability of the Knelsons to recover free gold. Secondary upgrading recovers slightly above 99% of the primary concentrate gold, 90% of it in a 65% Au concentrate and the balance in a heavily loaded (10 to 20 oz/st) pregnant solution. INTRODUCTIONBackgroundThe operating performance of the mill of Les Mines Camchib Inc. has been described earlier (Laplante et al., 1989). The presence of significant chalcopyrite (1 % and up) makes flotation necessary prior to cyanidation, to limit cyanide consumption and minimize environmental impact. In 1982, the presence of very high gold circulating loads in the grinding circuit lead to the commissioning of a gravity circuit, schematically shown in Figure 1. Gravity recovery of gold has been found beneficial because it increases metallurgical recovery by 1-3% (Laplante et al, 1987), as only part of the flotation tail is cyanided, and economic recovery, because of the lower net smelter return of gold in the flotation concentrate (as compared with the gravity concentrate). The latter increase is estimated, with a net smelter return of 95%, at 1.5% when gold recovery by gravity is equal to 30%. In early 1988, a sampling program was initiated to characterize the behaviour of gold in the grinding/gravity circuit. This paper reports on the results of this study."

Jan 1, 1990

By J. Ling, L. Racine, P. Cousin, A. R. Laplante

"The problem of gold recovery by gravity from high density gangues is first discussed from a fundamental perspective. Three potential difficulties are presented: poor liberation and fine gold particle size, concentrate bed erosion by coarse dense particles, and slow percolation of gold particle through the high density gangue bed. Two case studies are presented to illustrate the impact of these three problems on circuit performance and the feasibility of gravity recovery. It is concluded that careful testing can determine the scope of the first problem and feed preparation can limit the extent of the second. The third problem is clearly the most serious and results in lower gravity recoverable gold recoveries than would be achieved with the same recovery effort on a low density gangue application.IntroductionSince the commercialisation of the Knelson Concentrator in 1980, gold gravity recovery has experienced a surge in interest, in Canada and the United States first, then Australia, Zimbabwe and Russia, and finally worldwide. Table I details number of units sold in various countries, which corresponds approximately to their importance as gold producers 1. Exceptions. such as the low rank of South Africa or the importance of Zimbabwe, despite the much higher gold throughput of the former, are generally the result of differences in the effectiveness of the local marketing strategies, as well as a reflection of the ""philosophy of recovery"" prevalent in the country.The impact of the Knelson has not been felt equally in all plants. Typically, a highly successful application falls into the following categories: (a) alluvial or hard rock recovery for which gravity is the sole recovery method, (b) hard-rock free gold milling with ores which have a very high gravity-recoverable gold (GRG) content, (c) low grade sulphide copper-gold ores which include flotation ahead of cyanidation and (d) free-milling gold ores ahead of Other applications can be successful, but are not as common. The ""explosion"" of centrifuge concentration, of which the Knelson is the most successful but by no means the sole model, has created a certain euphoria which can be summarized as ""gravity recovery will improve the profitability of gold milling, no matter what."" This presentation is about applications that are not so successful, or even downright unsuccessful. The rationale is not to down-play gold gravity recovery, but to set it in its rightful position: metallurgically, it is not appropriate all of the times; it can become inappropriate if poorly designed; and it can be metallurgically possible but economically unjustifiable. In this paper, this will be illustrated and explained rather than demonstrated, with the use of both industrial plant surveys and laboratory test work. Alternate gravity approaches will be suggested."

Jan 1, 1997

By L. Connolly, F. R. De Luca

"Rubber liners at Denison Mines Limited are used in 10 1/2x 24' low discharg0 pebble mills. These were originally 10 1/2 x 13 Dominion overflow type ball mills. Experience here shows that the wear of rubber and ni-hard lifters is approximately the same in the feed end half of the mill, while the wear of rubber lifters is much greater in the discharge half. The wear of rubber plates is considerably less than white iron in the feed end half of the Mill and slightly more in the discharge end half of the Mill. Rubber components are lighter to handle but their installation is time consuming. This leads to the conclusion that a combination of ni-hard lifters a~~ rubber plates is the most economical compromise in Denison's case, for the Mill. Rubber discharge grates are superior to steel grates, while steel feed end liners are superior to rubber.The Use of Rubber Mill Liners at Denison Mines LimitedGrinding is done in two identic0al circuits each consist-ing of one 10 1/2 x 14' Dominion overflow rod mill, two Dorr Oliver quadraplex rake type classifiers, two 10 1/2 x 24' Dominion low discharge grate pebble mills and ancillary pumps and conveyors for pebbles. There is one centrally located distributor box that receives the discharge of the 4 pebble mills and splits it out to the classifiers."

Jan 1, 1974

"Air Products approached LAC Minerals in 1987 to initiate trials with pure oxygen in the leach circuit at several LAC facilities in Canada. This paper gives an overview of oxygen use and covers specific operating data from the Doyon and Terrains Aurifères mills near Val D'Or in northwestern Quebec. LAC also uses oxygen at the Macassa mill in Kirkland Lake, Ontario.In addition to the LAC facilities, oxygen is currently in use for test purposes at the Holt McDermott mine in Kirkland Lake, Ontario and the Camflo mine near Val D'Or.There are two requirements for oxygen in the cyanide leach mill. Firstly, oxygen is required in the familiar gold dissolution reaction as follows:(1) 4 AU (s) + 8 NaCN (aq) + 02 (aq)+ 2H 20(aq) - 4NaAu(CN) 2(aq)+ 4Na OH(aq)Of the reagents on the left side of the equation, the availability of gold is fixed by the ore in question. Obviously, water is available in excess, 1eaving cyanide and oxygen as the limiting constituents in the process. Most mills operate with an excess of cyanide, which is fairly closely monitored. Dissolved oxygen levels, however, are not normally watched very closely and find their own level based on the temperature, the availability of compressed air and the ability of the ore to consume oxygen.Typical D.O. levels are in the 3-8 ppm range, however levels less than 1 ppm are not uncommon for refractory ores.With pure oxygen, dissolved oxygen levels as high as 30 ppm can be achieved. (Figure #1). This greatly accelerates the kinetics of the leach reaction and may also shift the reaction further towards completion thus increasing gold dissolution slightly."

Jan 1, 1990

By A. H. Winckers

"The San Nicolás deposit is a complex fine grained polymetallic volcanogenic massive sulphide deposit located in central Mexico.Metallurgical testwork was carried out in 1999 and 2000 to develop a flowsheet. During the course of the metallurgical testwork it became evident that it would be impossible to develop an accurate head gradehecovery based model for the projection of metallurgy. It was suspected that variability in mineral texture was a predominate factor affecting metallurgy. For this reason it was decided to evaluate the applicability of QEM*SEM technology to this test program.This paper summarizes the metallurgical testwork and describes the evaluation and subsequent application of the QEM*SEM technology to characterize the mineral texture throughout the deposit. Finally it is shown how the QEM*SEM data are used in the mine block model to project the metallurgy.The QEM*SEM (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) is an automated image analysis system developed by CSRO which provides quantitative numerical estimates of the compositional and textural properties of the mineral suite which govern the concentration process.INTRODUCTIONThe San Nicolás deposit, was discovered in 1997 through the application of geological and geophysical techniques. The property lies 60 km southeast of the city of Zacatecas on the central Mexican plateau as shown in Figure 1."

Jan 1, 2002

By Paul Voigt, Mike Hourn, Glenn Stieper

Sable Zinc Kabwe Limited ("Sable") is a base metal processing plant, two kilometres south of Kabwe Town in Central Province, Zambia. The region has a rich history in mining and minerals production, being a major lead and zinc producer from the 1900s up to the mid-1990s. In 2006, a copper plant was built at the Sable processing site to treat third-party copper and cobalt oxide ores and concentrates. The oxide leaching plant included whole ore leaching, solvent extraction and production of 8,000 tpa LME Grade A copper cathode. The plant was placed on care and maintenance in 2014, and Glencore Plc ("Glencore") took the opportunity to convert the plant using a minimal budget, to an Albion Process™ plant to treat local refractory copper concentrates unsuitable or uneconomic for smelting. The Albion Process™ plant comprises an M100 IsaMill™ operating in acidic conditions such that raffinate from the downstream process is recycled back to slurry the concentrate delivered to site thus maximising copper tenor in solution and reducing water consumption. The finely ground concentrate feeds an oxidative leaching plant using the existing stainless steel oxide leach reactors converted to Albion Process™ duty by fitting HyperSparge™ supersonic oxygen injectors and gas dispersing agitators. The leached slurry is then directed to the existing solid/liquid separation equipment, and the PLS is then sent to the existing SX/EW plant. The plant also allows for cobalt recovery from the raffinate. The plant was designed based on testwork on regional copper concentrates. The plant was designed to toll treat a range of concentrates, and so the design was flexible With the flexibility of the Albion Process™ being one of its distinct advantages, the plant was ideally suited for tolling regional concentrates. The plant was commissioned and ramped up in six weeks using low-grade Zambian copper concentrate, and produced exclusively LME Grade A copper with over 99% leach recovery in the Albion circuit. INTRODUCTION The Sable Zinc Kabwe Limited ("Sable") process plant is located 2 km south of Kabwe town and 140km north of Lusaka in Central Province, Zambia. In 1902, rich deposits of zinc and lead were discovered with mines and processing plants operating in and around the town until mid-1994. In 2000, the Kabwe Mine tailings dams were sold to Sable, a newly established company, as part of a purchase deal for other plots and facilities. Up until 2004, Sable produced zinc cathodes in an SX/EW plant treating wash plant tailing material. In 2004, Sable was acquired by the South African mining company Metorex Limited ("Metorex"), and in 2006 a copper/cobalt SX/EW plant was built to produce copper cathode from malachite ore supplied from the Democratic Republic of Congo. In 2011, Jinchuan Group International Resources Co. Ltd acquired Metorex and Sable was in turn sold to a subsidiary of Glencore Plc ("Glencore").

Jan 1, 2019

Reaction between xanthate ions in solution and oxidized compounds present on the surface of galena to form lead xanthate is considered to be a side reaction not contributing to flotation, although accounting for some consumption of reagent. The direct reaction of lead sulphide with xanthate and oxygen to form lead xanthate is the most significant to flotation. Coadsorntion of dixanthogen is also involved. Previous work has shown lead recovery in lead rougher flotation to be a function of m [H+] where: m = concentration of xanthate in solution rHl = hydrogen ion concentration. A plausible explanation for this relationship is suggest-ed. Likewise, the experimental findings that the amount of xanthate adsorbed under certain conditions is a function of m'[H+] are explained in terms of reaction between xanthate ions and soluble basic lead salts such as PbO.PbS04? It is also shown that m[H+] should have a constant value in lead cleaners operating at a higher pH than the roughers. This conclusion is confirmed by plant data, and the value of the constant agrees well with the calculated value. The finding is useful in mill control.

Jan 1, 1965

By Milton C. Graves, Marcos Zentilli

"Gold has been reported from most geological environments in Nova Scotia; however, virtually all production (circa 2,000, 000 troy ounces; circa 60 tonnes) has come from that part of the province to the south of the Glooscap Fault which is underlain by Lower Paleozoic rocks of the Meguma Group. Over fifty concordant sets of quartz-carbonate-arsenopyrite veins have seen production. The host rocks are greenschist-grade equivalents of Cambro-Ordovician flyschoid quartz wackes and shales folded and metamorphosed during the Devonian Acadian Orogeny. The veins were emplaced under conditions of greenschist-grade regional metamorphism and under the same conditions of tectonic stress that later resulted in the regional folds and penetrative, axial-plane slaty cleavage. Rapid filling of hydraulic fractures caused by excess metamorphic pore fluid pressure under Acadian tectonic stress conditions can account for the geometry and paragenesis of these veins.The ultimate source for gold deposits in most greenschist-grade domains remains in doubt, but these domains seem to have had ample gold within them available for mobilization. The work done, to date, on the gold geology of Nova Scotia suggests that regional greenschist metamorphism was an effective mobilizer and a potential concentrator of Au, As, W, Fe and S from these vast reservoirs.In rocks of pre-Acadian age north of the Glooscap Fault, gold occurs as an important accessory in volcanogenic massive sulphide ore, as a minor constituent in other types of basemetal concentrations and in one small concordant group of quartz veins.The post-Acadian metallogenetic domain, which overlies and overprints the two older domains, contains small amounts of gold in many mineralizing environments. Veins, with stibnite and gold, cross-cut crystalline rocks. Disseminated gold is present in basal conglomerates of post-tectonic molasse. Gold has been a by-product of Mississippi Valley-type Pb-Zn-Ba-Sr deposits in Lower Carboniferous sedimentary rocks and has been reported with Pb-Zn-Ba-F in veins which cross-cut Lower Carboniferous and older rocks. Small post-glacial placers have also seen minor production."

Jan 1, 1982

By Mike Robotham

When RFQ?s are received they often contain detailed technical specifications which suggest a departure from the suppliers own customary approach to the design. Both client and end user are quite rightly influenced by their own experiences. The question is who is right, the client and his consultant, the supplier or perhaps a combination of these. This paper looks at some of the fundamental variances that often occur in the approach to the mechanical design of drum hoists, based on our experiences of recent years. Director of Engineering, Mike Robotham is a chartered engineer and has been with DavyMarkham for over 30 years. Having completed a craft apprenticeship he later joined the engineering department as a junior engineer. He has a wealth of experience of working on medium to large engineering projects in the field of mechanical, electrical and hydraulic equipment

May 1, 2011

By Victor Azbe

Azbe System of Controlled Calcination To obtain good and cheap lime there are certain fundamental requirements that need to be satisfied. These are : (1) Proper combustion of fuel and steady supply of heat to the kiln. (2) Proper heat distribution in the kiln. (3) Uniform drawing of lime through the several shaft sections. (4) Complete cooling of the lime and recovery of the heat. (5) Temperature control of the hot zone by economical means. (6) Ample draft to obtain high capacity. (7) Arrangements to facilitate operation. Figure 17 shows diagrammatically one of the smaller kilns, intended for large stone. Such a kiln can be supplied with gas from a centrally located automatic gas producer, or, as shown, from an integral producer located snugly against the kiln. These producers make very good gas and have a gasification capacity of either 10 or 15 tons of coal a day. The producers have water-sealed ash pits, a rather thick fuel bed that is conducive to the making of high-CO gas, and are under forced draft. No steam is used. Clinkering is prevented by admixing some spent gas from the kiln with the air. Coal feeding is from a coal bunker through spouts into the hoppers over the producer. This is done, at proper intervals, by manual operation of slides, but it is planned to install mechanical feeders. Central mechanical gas producers have the advantage of requiring little labour, but the blowing of soot is a problem, as also is the proper distribution of the gas among several kilns. In the case of integral gas producers, soot from the centre burner is blown back into the producer to be burned, and the supply of gas to the kiln is controlled by regulation of air to the producer. In large plants, the mechanical producer may be preferable, but in small ones, the integral producer is cheaper, better, and more reliable. The kiln shown in Figure 17 is suitable for both systems of gas supply. It will be noticed that there are no side gas burners. All gas enters the kiln through the centre burner in a manner that permits any desired amount of gas to be directed to any of the kiln sections by the aid of regulating slides.

Jan 1, 1946

By Luis Magallanes-Hernández

"Industrias Peñoles, S.A. de C.V. (Peñoles) in Mexico, is a major silver producer. The Peñoles Mining Division has eight Mining Operations and in seven of them, flotation is used to concentrate the metal and mineral values. Common metals and minerals values are: metallic gold and silver, gold-silver alloys, silver sulphide minerals (acantite, pyrargirite, argentite, proustite); lead sulphide mineral, galena; zinc sulphide mineral, sphalerite; and copper sulphide minerals (chalcopyrite and bornite).In the last years, a special emphasis has been given to using modal analysis to identify ore mineralogical limitations, in order to direct efforts into key areas where opportunities exist to improve the metallurgical results.This work aims to share Peñoles mineralogical and metallurgical results, through presenting, discussing and drawing conclusions on these results; as well as pointing out areas where more work is needed to improve the Concentrator´ performance.PEÑOLES BACKGROUNDPeñoles´s mission is to add value to non-renewable natural resources on a sustainable manner. It was established in 1887, and it is a mining group with integrated operations in smelting and refining non-ferrous metals, and producing chemicals. Peñoles is the world’s top producer of refined silver, metallic bismuth, and sodium sulphate, the leading Latin American producer of refined gold, lead, and zinc.Peñoles Mining Division is integrated into eight mining business, located on five different states in Mexico. Metal productions for the Mining Division during 2003 were: 343 thousand gold ounces, 48.4 million silver ounces, 81.3 thousand tons of lead, 235.1 thousand tons of zinc, and 10.6 thousand tons of copper."

Jan 1, 2005

By S. Bellec, P. Champagne, J. Châteauneuf, A. Berton, S. Fortier

"The start-up of new plants, extending from the commissioning of equipment to the production ramp-up, is a critical period where the processing circuit operation must be done in a structured and well controlled way to enable the gradual, safe and rapid achievement of production targets. The magnitude of the many risks associated with this pivotal period is accentuated in the actual context of low commodity prices. However, the implementation of a method that analyzes risks associated with a start-up, their probability of occurrence and their impacts leads to the identification of a series of preventive actions that can be applied in order to reduce potential negative impacts.Soutex has been involved in numerous start-ups over the last few years and has developed a structured methodology to assess this crucial period, maximize the pre-start-up preparation, ensure a smoother and safer ramp-up period and minimize the time needed before reaching commercial production.This paper describes a method to identify preventive actions to apply in order to reduce risks related to a plant start-up. Then, the various steps of the method are demonstrated using the industrial case study of the Canadian Malartic gold plant situated in Abitibi, Québec. The specific preventive actions, during start-up, the organisational measures and the ramp-up plan are detailed as they were effectively achieved. Finally, the post start-up actions are presented as well as some key results illustrating the achievement of their prior defined objectives.IntroductionPlanning a new plant or new circuit start-up in a mine installation involves various risks, both at the economical and safety levels. Unprepared staff and equipment can lead to safety issues that could threaten plant staff as well as the environment. Moreover, a poorly prepared start-up could often lead to equipment break-down, production stoppages and delays, leading to important economic impacts, delaying commercial production and therefore affecting directly the profitability of mining projects.It is common in the industry to have structured commissioning procedures for major equipment taken separately. Technical personnel from the equipment manufacturing company would usually come on site in order to perform the pre-operation verification, dry runs and the first hours of operations. This kind of assistance is usually focussed on one piece of equipment and neglects the interactions between the various equipment of the production chain. The commissioning phase is usually maintenance oriented and the information given by the manufacturing representative seldomly flows through the operation staff (in the case of this paper, the denomination “staff” refers to both managing and operating employees). The global process is usually not taken into consideration by the technical personnel sent on-site by the manufacturer during the commissioning phase. Many papers can be found describing the commissioning of new equipment focussing on the technology (Côté and Adante (2009), Wells et al (2007)) but without dealing with its integration process in the complete production chain."

Jan 1, 2016