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By Gordon Lewis

The Penjom Gold Mine is one of the world's worst preg-robbing gold ores, yielding very low recoveries from traditional CIL methods. Gold recovery from the cyclone underflow was targeted to recover as much gold as possible in the absence of the fine preg-robbing carbon. Gold is recovered by intensive cyanidation and tabling of a gold concentrate produced by gravity from the cyclone underflow. The circuit was designed together with Gekko Systems and uses their InLine Pressure Jig and InLine Leach Reactor technology to reject the preg-robbing carbonaceous material and obtain high recoveries from the gravity concentrate before over grinding the carbon and sulphides. The gravity and intensive cyanidation circuit now recovers almost 50% of gold in new mill feed, with unit recovery in intensive cyanidation of up to 90%, the highest unit recovery in the plant. Operating costs for the gravity and intensive cyanidation circuit are under US$2.50 per oz, while the cost to recover gold from the cyclone overflow is -US$200 per oz. (not including common costs of milling, stripping and electrowinning). Figure 1 shows the increase in gold recovery due to the gravity and ILR circuit coming on line at Penjom.

Jan 1, 1999

Develop a method for recovering phosphate from a wide variety of complex western phosphate materials, including low-grade ores, tailings, and unused fines. Approach A flotation technique is used for this broad type of extraction. The method includes depression of phosphate minerals and anionic flotation of carbonate minerals, followed by cationic flotation of silicate minerals. How It Works A slurry is prepared for flotation by sizing to remove a low-grade, high-impurity slime fraction. Depending on the material, further sizing and/or grinding steps may be used to produce a size concentrate or to remove gangue. The flotation feed is conditioned with H2SiF6 and a fatty acid emulsion. The H2SiF6 is absorbed chemically to the phosphate mineral surface, making it strongly attracted to water and preventing adsorption of the fatty acid. Under these conditions, the fatty acid is a selective collector for carbonate minerals, which are removed as a froth product. Next, the silicates are floated with an amine reagent added directly to the slurry without additional pulp preparation.

Jan 1, 1982

By Brommerm Tracey, Britt Elin Gihleengen, Elsa Olivetti, Hans Ole Riddervold, Randolph Kirchain, Geir Øyen

"Compositional uncertainty in secondary materials and variable processing conditions inhibits secondary material utilization in the production of aluminum alloys. Efforts to implement optimization models that direct batch planning have limited industrial presence due to factors such as the insensitivity of these optimization models to dynamic plant circumstances. This paper describes a chance constrained model formulation that generates lower cost, robust batch plans with significant flexibility towards changes in processing conditions. The principal attribute of the chance constrained formulation is its inherent mitigation of risk by diversifying the batch plan. This paper compares aluminum remelter batch planning using the chance constrained formulation with a traditional deterministic model and a manual batch planner. With the expectation that volatile material prices, restricted scrap material availability, and pressure by consumers and legislation for increased recycled raw material input will continue in the future, batch planning tools that inherently diversify a production portfolio will become increasingly advantageous for industrial aluminum remelters.IntroductionAluminum remelters must develop strategies to incorporate lower cost secondary materials into finished alloys to remain competitive amidst increasingly demanding market and regulatory conditions. Determining the optimal combination of incoming raw materials to produce an alloy that meets compositional specifications presents remelters with a complex problem that has driven the development of computational tools commonly referred to as batch planning or blending algorithms. The ubiquity of the ingredient or raw material blending problem in production has motivated ongoing development of batch planning algorithms since the classic nut-mix problem in the 1950's [1]. The most common model formulation for industrial aluminum remelters are deterministic, linear optimization programs [2]. These blending problems determine the optimal combination of raw materials by minimizing cost subject to constraints around demand, availability, and compositional specification. Despite extensive research and moderate computational requirements, batch planning algorithms are inconsistently used in industry. Insufficient incorporation of the complexity of real world remelting conditions into these models provides an obstacle for their implementation [3]. For example, many batch planning algorithms do not explicitly incorporate the impact of compositional variation of the raw materials on overall batch cost. Additionally, they do not allow for endogenous specification of tolerance to error in batch planning, so provide little flexibility where a batch planner would like to incorporate materials of greater uncertainty. Incomplete accounting for quality variability undervalues secondary materials leading to overly conservative use [ 4, 5]."

Jan 1, 2011

By Caio Trindade Almeida, Tharcysio Oliveira Rocha Paiva

Tharcysio de Oliveira Rocha de Paiva2

Oct 3, 2019

The large increase in secondary industries in this country, during the war and post war periods, has caused a shortage of capacity for the production of merchant bar.To overcome this shortage, an expansion of rolling mill facilities has been undertaken by the Broken Hill Pty. Co. Ltd. A small, but modern, merchant mill has been erected at Kwinana in Western Australia and a strip and skelp mill is under construction at Newcastle. The latter mill will roll strip and skelp at present being rolled by the Newcastle 10 in. Merchant Mill, enahling this mill to concentrate on merchant bar production.The Kwinana mill was installed to supply the Western Australian market. This state has a small population (approximately 658,000) and is not at present highly industrialised. It was necessary, therefore, to design a mill which would be capable of producing a wide diversity of sections and could be expanded as the demand increased. To begin with capital expenditure had to be kept within reasonable bounds. The design work for this mill, with the exception of a few specialised items of equipment, was carried out at Newcastle.All design work for the Newcastle mill was carried out by the lVIorgan Construction Co. of America. Although initially intended for rolling flat. products, the designers were asked to make the mill as flexible as possible, so that should the market for flat products decrease, this mill with additional equipment could undertake the rolling of medium sized sections.

Jan 1, 1957

By Earl A. Berry

Someone once said, "The safest mine is one in which no one goes into." We all recognize this as being perhaps wishful thinking. We also recognize in it a certain amount of truth and an ultimate goal if we are optimistic. All of us are aware of the many things that have been done, are being done and will be done to reduce manpower in mining. For those of us; who are optimistic about this ultimate goal it would appear from the records-we are more than well on our way to the so called safest mine. Let us see what has been done in the past 20 years. T e period from 1935 to 1956. For example in the coal mining industry: In 1935 there were employed 462,903 men who produced an average of 805 tons per man per year or 4.50 tons per man per day. In 1955 there were employed 225,093 men who produced an average of 2,064 tons per man per year or 9.84 tons per man per day. There are no comparable figures compiled for the metal mining industry as a whole that can be broken down in this manner. However, from examination of figures available for different groups in metal mining there is a trend similar to that in coal mining. No-dbout the above figures reflect the intense development and perfection of machines and mining systems to tear out, transport and process our mineral wealth. The figures also show the mining industry has been able to double its production and at the same time reduce its manpower by half. When you compare the number of men employed today with the number which would have been employed 20 years ago to gain todays production at that time it become apparent that greater safety has been accomplished. For example the years 1935 to 1956 for all mining show. In 1935 there were approximately 649,226 men employed in mining and reports show 1,399 fatalities and 74,913 non-fatal injuries. In 1955 when there were 313,883 men employed in mining 496 fatalities and 25,365 non-fatal injuries were reported. To have produced the same tonnage of material in 1935 that was produced in 1955 it would have required the employment of approximately 1,298,452 men. 2,798 could have been fatalities and 149,826 could have had non-fatal injuries. You can now measure the full impact of what has been accomplished in the past 2o years by the aggressiveness of mine management, the wizardry of our engineering personnel and the thoughtfulness and devotion of our safety people and their programs. Therefore, there is a trend towards the goal of our opening statement. We whoare toptimistic believe this trend will accelerate at a-faster pace. Why? Because anyone engaged in the mining industry today can well afford to invest a minimum of $30,000.00 in capital equipment todisplace the labor of one man. This fact alone is a terrific incentive for mine management to apply and manufacturers to develop equipment of a type to get the men out of the mine. Now you can determine this problem not only becomes one of safety but also one of economics, When productivity is stepped up and manpower reduced management is learning the hard way what it means to them; in the profit and los s column when a few minutes of delay or downtime of costly machines and processes occur. They have learned that fast and efficient communication systems are the best means of combating breakdown, delays, bottlenecks, supply problems, the saving of lives and property and increasing production. One large western metal mine was able to increase Its tonnage by 4000 tons a day by using modernup to date electronic type communication system. The National Coal Board of Great Britain recently allocated 45,000,000.00 to study and develop faster and more efficient communications when a survey indicated what a serious bottleneck poor communication in their present systems of mining turned' out Lobe.

Jan 1, 1958

By A. Allaire

The Goldex operation of Agnico-Eagle Mines (AEM) commenced operations in the spring of 2008. Following some months of initial operation, the grinding circuit capacity was under-performing according to the original design throughput. BBA Inc. (BBA) was commissioned, in February 2009, to study the different options and recommend the quickest and most cost-effective solution to increase the grinding circuit throughput rate. The mandate was to increase the throughput of the grinding circuit to beyond the original design of 7,000 tpd to 8,000 tpd or greater, while retaining the existing SAG and ball mills. The circuit was modelled using JKSimMet software to evaluate the different options, each with a number of different operating parameters. The option of secondary crushing of the SAG mill feed was retained. Comparison of the different options and simulation outcomes, design of the secondary crushing circuit, operating conditions, and initial adjustments in the design and operating results of the new grinding circuit are discussed in this paper.

Jan 1, 2012

By D. Runnels, A. Allaire, J. Fournier, Y. Sylvestre, F. Robichaud

The Goldex operation of Agnico-Eagle Mines (AEM) commenced operations in the spring of 2008. Following some months of initial operation, the grinding circuit capacity was under-performing according to the original design throughput. BBA Inc. (BBA) was commissioned, in February 2009, to study the different options and recommend the quickest and most cost-effective solution to increase the grinding circuit throughput rate. The mandate was to increase the throughput of the grinding circuit to beyond the original design of 7,000 tpd to 8,000 tpd or greater, while retaining the existing SAG and ball mills. The circuit was modelled using JKSimMet software to evaluate the different options, each with a number of different operating parameters. The option of secondary crushing of the SAG mill feed was retained. Comparison of the different options and simulation outcomes, design of the secondary crushing circuit, operating conditions, and initial adjustments in the design and operating results of the new grinding circuit are discussed in this paper.

Jan 1, 2012

By Dennis Ofiara

Several recent tunnel jobs have required special adaptations of hard rock TBMs. Some of the special job conditions are ?no blast? launch requirements, small shafts or launch pits, proximity to existing underground structures, and short tunnels where the TBM must be retrieved through the primary lining. This paper describes a few of these projects, and the machine adaptations that have made TBM excavation feasible.

Jan 1, 2008

By P. R. Dugan

Sulfur removal from high sulfur coal has several objectives including: a) reduction of the atmospheric load that contributes to the problem of acid precipitation; b) reduction of ash, which contributes to decreased energy transfer in boilers, as well as ash disposal; and c) alleviation of the social and economic dislocations related to uneven geographical distribution of sulfur in coal reserves. Cost in relation to the value of refined coal will govern the development of an emerging coal refining industry. Estimation of the premium paid by power companies for coal with a low sulfur content is a good estimate of the value that will be added as the result of refining. Estimates of premiums paid in 1984 are $28.65/t ($26 per st) for reduction of total sulfur from 370 to 1% S and greater than $28.65/t ($26 per st) for removal below 170 sulfur.

Jan 1, 1988

By E. V. Manlapig, M. A. Hampton, M. E. Holuszko

Methanol treatment of ZnS particles has been found to remove slimes and facilitate flotation. The removal of slimes renders the ZnS surface more hydrophobic, resulting in an increase in the hydrophobic attractive force between the particle and bubble. Hallimond tube flotation, induction time measurement and particle-bubble force analysis with the atomic force microscope (AFM) was undertaken to link the beneficial effect of methanol treatment of ZnS particles to their increased floatability.

Jan 1, 2009

By M. R. Coffin

In recent years, improved operation of the Kidd smelter has resulted in an increase in blister production capacity. Due to manpower and equipment limitations anode production and treatment rates could not be increased without incurring significant additional operating expenses. The option chosen to expand casting and refinery capacity to meet the available blister supply was to increase the anode thickness while maintaining the same anode exchange cycle in the refinery. This has resulted in a cathode production increase of almost 10% for minimal expenditure. Equipment and process modifications required to cast and refine the thicker anodes are discussed in this paper, along with the Six Sigma methodologies used to identify them. Key areas covered are Hazelett continuous caster operation, refining process parameters, plating performance and cathode quality.

Jan 1, 2007

By Joseph T. Roy

MINING revival during the last few years has brought about a considerable increase in the number of gold and silver determinations made, noticeable in all branches of the industry but especially so in the business of a custom smelter. At East Helena, solely a custom smelter the assay department found that the four assay furnaces available were inadequate to handle the increased amount of work. These furnaces were of a standard design, having duplex muffles, one superimposed on the other; each muffle was 12 1/2 in. wide, 18 1/4 in. long and 6 in. high, and could handle 72 cupels or 20 fusions. Since the heat varied considerably between the upper and lower muffles, cupellations were not ruin in both at the same time. To speed up assaying, E. A. Meale, chief chemist, had the happy idea of enlarging a muffle furnace, originally designed by the Montana Power Co., so that one muffle would acconmmodate at least as many determinations as the duplex muffles. An order was given to the Denver Fire Clay Co. for a Carbofrax muffle of the size required and the local engineering department enlarged the furnace to accommodate the muffle. Details of the

Jan 1, 1938

By Y. C. Lo

Grinding process optimization is an exciting new tool for maximizing the performance of existing mineral processing plants. This paper discusses the methodology of optimization which involves plant sampling, pilot tests, modeling, computer simulation and plant verification. The methodology developed emphasizes the interactions among operating variables and design options. Two example applications demonstrate that AG and SAG optimization provides the basis to increase grinding throughput up to 10 percent. This sys- tem optimization technology has been proven to be very cost effective for grinding plant performance improvement.

Jan 1, 1998

By C. Dirscherl, M. Combes

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71% - as confirmed by real operational data from the Antapaccay mine in Peru. It was the first plant worldwide to use gearless drives for both applications.INTRODUCTION – THE GEARLESS PRINCIPLE The principle idea behind a gearless drive system is to reduce the number of components and diversity of parts. Especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material. In order to apply this principle of simplification we will take a look at the components of a conventional drive system consisting of: - Driven equipment (mill, conveyor, slurry pump) - Components altering the rated speed (gearboxes, girth gear / pinion) - The electric motor - Starting devices for the motor (VSD, CCV, LRS, clutch), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage - Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation - The electrical supply system (cables, switchgear, transformers, protection equipment)"

Jan 1, 2014

By C. Dirscherl

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train, the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71 percent — as confirmed by real operational data from the Antapaccay Mine in Peru. It was the first plant worldwide to use gearless drives for both applications.The gearless principleThe principal idea behind a gearless drive system is to reduce the number of components and diversity of parts, especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material.In order to apply this principle of simplification, the components of a conventional drive system are examined. They consist of:• Driven equipment (mill, conveyor, slurry pump).• Components altering the rated speed (gearboxes, girth gear/pinion).• The electric motor.• Starting devices for the motor (VSD, CCV, LRS, clutch), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage.• Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation.• The electrical supply system (cables, switchgear, transformers, protection equipment)."

Jan 1, 2015

By C. Dirscherl

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71% - as confirmed by real operational data from the Antapaccay mine in Peru. It was the first plant worldwide to use gearless drives for both applications. KEYWORDS: Gearless Mill Drives, Gearless Conveyor Drives, Availability, SAG Mill, Ball Mill, Overland Conveyor, Antapaccay INTRODUCTION – THE GEARLESS PRINCIPLE The principle idea behind a gearless drive system is to reduce the number of components and diversity of parts. Especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material. In order to apply this principle of simplification we will take a look at the components of a conventional drive system consisting of: - Driven equipment (mill, conveyor, slurry pump…) - Components altering the rated speed (gearboxes, girth gear / pinion) - The electric motor - Starting devices for the motor (VSD, CCV, LRS, clutch…), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage - Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation - The electrical supply system (cables, switchgear, transformers, protection equipment) Intermediate gearboxes are not required when a motor is used with a rated speed that directly matches the speed requirement of the driven equipment. Furthermore the VSD can be used to smoothly start the motor and to vary speed during operation, which means that it satisfies both requirements."

Jan 1, 2015

By Terry L. Cook

RAG Coal West, Inc., Belle Ayr Mine is located in the heart of Wyoming’s rich Powder River Basin coalfield. Belle Ayr utilizes an open pit, truck/shovel operation to strip the overburden off the 70’seam of sub bituminous coal. Our excavation capacities consist of a 301 Marion with a bucket size of 52 cubic yards, and a 4100 XPB P&H with a capacity of 76 cubic yards. Production levels on these machines are closely monitored utilizing the Modular Mining Dispatch system. RAG Coal West, Inc. is a coal mining business that utilizes the effectiveness of teams as one of their strategies. Technicians have a certain amount of control over their own Team Process. The Drilling & Blasting Team is an assortment of blasters with varying experience levels. We have been able to think outside of the box when it comes to certain “proven” methods of blasting.

Jan 1, 2004

By S. A. Ziebold

There is often a need to increase capacity through existing mist eliminator installations without significant tower modifications. Often there is not enough extra space outside existing vessels unless more expensive changes can be justified. Also, plant downtime must be considered. The challenge in retrofitting is to overcome velocity limitations inherent in the design while at the same time extend performance capability. The solution most often is to create new ways to add extra filter area while remaining constrained to the existing space. This strategy, however, can dangerously backfire if basic design principles are not followed. Mist eliminator design is a complex integration of many conflicting performance parameters. Often the objective is to increase scrubbing capacity while maximizing collection efficiency and service life and minimizing operating pressure drop (energy cost), particle regeneration (re-entrainment) and overall maintenance costs. Results of plant retrofitting using mesh pads, impaction fibre beds and diffusion fibre beds are presented based on actual plant projects. Often the retrofit project can be more effective by increasing the scope and combining other new plant equipment with the upgrade such as new tower components. In some cases, the type of mist eliminators can be upgraded from impaction type (velocity dependent) to Brownian diffusion type (velocity independent) if additional downstream protection or reduced emissions are desirable, especially at turndown rates. Trade-offs between different fibre bed types and styles are discussed as they relate to performance and maintenance.

Jan 1, 2007

By J Wheeler

The objective of this paper is to examine the operation of high frequency screens in closed circuit grinding, where the outcomes achieved indicate favourable economic gains at the comminution stage and downstream processes, including flotation, dewatering, and filtration operations. The classification process in grinding circuits has been slowly evolving within the last century. The history of classification devices brings to mind rake classifiers and spiral classifiers, which although having higher efficiencies compared to hydrocyclones, were not able to keep pace with the evolution of concentrator equipment treating higher tonnages. This higher tonnage throughput has tended to drive the concept of utilising hydrocyclones as the classification stage in closed grinding circuits. The comminution process is commonly the most energy intensive stage of mineral processing. Researchers have determined that the classification stage in the comminution process has the greatest potential for improvement. This paper is intended to inform mineral process engineers of the benefits that high frequency screens offer over hydrocyclones. This will be done by reviewing the purpose for the evolution of classification in the comminution process, documenting past and recent studies, and explaining the modern technology that is currently available.

Aug 8, 2011