Search Documents

By Michel Brissette

"To recover more valuable ore and considering the complexity of minerals, the needs to grind finer is increasing. To reach the desired fine grinding targets, using the existing grinding media size, the energy consumption is increasing exponentially. As already proved at this conference, small grinding media represents the best potential to improve grinding efficiency. How do the small grinding media perform in industrial grinding mills?The use of small grinding media in regrind mills proved that finer grinding can be achieved at lower energy consumption. In ball mills, smaller grinding media versus 25 mm media generate a power saving from 10% to 44%. In vertical stirred mills, the power saving increases from 20% to 60%. More potential savings have been identified.For the same operating conditions, how a vertical stirred mill is performing compared to ball milling? In regrind application, a vertical stirred mill with small media (5-12 mm Millpebs) will require at least 62% less energy than a ball mill charged with 25 mm grinding media.INTRODUCTIONIn some mining applications, fine grinding is needed to liberate further the valuable ore. The purpose of regrind mills is to achieve the last stage of grinding before final flotation stage: the cleaners. In part because of high prices of small grinding media as well as availability, the most widely used size of grinding media is 25 mm.When calculating the recommended ball top size from Bond’s formula (Bond, 1961), the size for regrind applications is much lower than 25 mm. Today, the barrier for small grinding media is broken. They are best suited in regrind application. The size of grinding media is one of the most important variables affecting the mill efficiency (McIvor, R., 1997; Nesset, J.E., Radziszewski, P., Hardie, C. & Leroux, D.P., 2006).Conventional ball milling was discarded for fine grinding because of its very poor energy efficiency (Zheng, J., Harris, C.C. & Somasundaran, P., 1994; Yan, D.S., Freeman, M. & Dunne, R., 1995). Therefore, new technologies as stirred mills were developed to grind finer more effectively. Three fundamental questions should be asked. What is the best fine grinding technology? What should be the best media size to use? Is it possible to grind finer by using less energy with the existing regrind equipment?"

Jan 1, 2009

By G. L. Zhu, Y. F. Wu, H. Nagaumi

A novel eutectic-type alloy Al12Si-HTC with high thermal conductivity has been developed by strict chemical composition control and heat treatment. The thermal conductivity of the alloy is about 30 % higher than that of current commercial Al12Si alloy. The Al12Si-HTC alloy has a silicon content of 10~12 wt.%, which provides excellent castability. Trace element strontium or calcium is added to modify eutectic silicon, and contents of transition elements such as copper, manganese are controlled in a low level. By appropriate heat treatment, thermal conductivity of the castings increases by 7.5 % and finally reaches 172 W/(m·K). It is found that eutectic silicon modification which makes average particle size finer than 2µm plays a dominant role in improving thermal conductivity, as well as further spheroidization of eutectic silicon and reduction of lattice defects in a-Al microstructure in subsequent heat treatment process. The alloy is successfully applied to produce a certain communication enclosure with complex finned structure by die casting process in industrial scale. The results of numerical simulation and thermal analysis experiments show that when manufactured by Al12Si-HTC alloy, the surface temperature of chips in the enclosure is reduced by 2.0~4.5 ? and the temperature distribution is more homogeneous compared with traditional Al12Si alloy.

Jan 1, 2015

By W. R. Leeder

"The Quintette coal property lies in the Rocky Mountain foothills of northeastern British Columbia (see Figure 1). Quintette and the adjacent Bullmoose property of Teck Corporation are soon to become the first commercial coal mines in the Peace River Coal Field, which is estir1ated to contain 10 billion tonnes of metallurgical coal reserves.Denison Mines Limited acquired the original Quintette coal licenses in 1969 and 1970. Exploration began soon after and the first feasibility study was conducted in 1975. Denison devoted the following six years to extensive planning and feasibility studies of the project. During this period, the provincial and federal governments also undertook studies to assess infrastructure requirements and economic viability of development in this part of the province. Many of the proposed mine sites such as Bullmoose and Quintette were at least 100 to 150 kilometres from the towns of Chetwynd and Dawson Creek, the nearest centres serviced by good highways and a railroad, and a complete network of services would have to be provided if such mines were to be developed. The overall project became known as the North East Coal Development.Concurrently with the feasibility studies, numerous technical and sales missions to Japan were made by representatives of Canadian industry and government, culminating in January 1981 with agreements for Quintette Coal Limited and Teck Corporation to supply a total of 115 million tonnes 8 million tonnes per year for 15 years of primarily metallurgical coal to the Japanese Steel Industry."

Jan 1, 1983

By Patrick Cloutier

Presentation objectives ? Introduce discrete-event 3D computer simulation as a tool to design, improve and optimize construction projects: ? Describe a real typical construction project planning issue. ? Present an applied use of simulation to solve this issue. ? Detail benefits of using simulation versus traditional planning methods.

Aug 1, 2013

By Bryan M. Maybee

The scheduling of underground mining activities is a complex task, in particular because of the requirement to satisfy a large number of constraints. A Schedule Optimization Tool (SOT) for underground mine planning is described, and its use for investigating strategic decisions is illustrated by means of a case study. The main components of SOT include: a genetic algorithm, which searches for optimal schedules; guidance, the application of heuristic rules to guide the genetic algorithm; and sliding, which implements just-in-time development. For the case study, SOT is employed to generate schedules at various ore capacities, accounting for the appropriate financials in each schedule evaluation. The case study finds that preliminary scheduling performed before invoking SOT, intended to provide a good starting point for the search, does not ultimately lead to higher value schedules. Two key uses for SOT are identified. A mine planner can save time by using SOT to produce high-value scheduling alternatives. This process ensures a broader investigation of the value that the deposit can yield. Also, SOT can be used to validate strategic and tactical decisions, by scheduling under alternative scenarios. Both uses produce high value schedules conforming to all imposed resource constraints.

May 1, 2009

By Tony Lipiec, Greg Gosson

"When it comes to new mines being developed, there is a general industry consensus that most low-hanging fruit has been picked. Many projects currently in the mine development pipeline have been around for decades, but were held back because of technical challenges. Future development of these deposits will likely require access to the public capital markets, and in Canada that means providing scientific and technical disclosure on these deposits in compliance with NI 43-101. As many of these “challenged” projects have metallurgical issues, the companies that own the projects need to ensure their metallurgical Qualified Persons provide transparent disclosure regarding proposed solutions to those issues.This paper provides an overview of the disclosure requirements under NI 43-101 that are pertinent to metallurgists, and other Qualified Persons who prepare technical disclosure regarding the metallurgical characteristics of a mineral project. It lists the triggers for a technical report under NI 43-101 and Canadian stock exchange policies, and identifies the sections of the report that should involve input from a metallurgist or process engineer. It briefly outlines new civil liabilities under Canadian securities laws that increase the possible consequences for not complying with the technical disclosure standards.These materials are provided for general information purposes only and do not constitute legal advice. Readers are advised to seek specific legal advice from their own legal counsel in relation to any decision or course of action contemplated."

Jan 1, 2003

By ANNE FUZESY

Soluble potassium salts in bedded underground salt deposits supply most of The world demand for potassium f or agricultural and industrial use. The potassium salts, sylvite and carnallite, were f irs, noted in drillcores in southern Saskatchewan during The search for oil and gas in ihe early /940s. Problems in shafi sinking beset pioneering potash companies, however, and cominuous production did no, begin uniil 1962. Powsh deposits in southern Saskatchewan occur within ihe uppermost 60 111 of the Middle Devonian Prairie Evaporite a, depths in excess of 900 m. Four groups of po/ash-bearing haliie beds have been distinguished: the Esierha-::,y, White Bear, Belle Plaine and Paiience Lake members. Powsh deposiis extend a jell' kilomeires into Manitoba and south imo orth Dakoia and non heasiern Moniana. Individual potash-rich beds are extensive and consistent in grade and Th ickness. Local th ickening occurs where carnallite is the dominani poiash mineral. Th e preferred ore, sy lviniie, is a clean mixiure of sylvite and haliie. Carnalliie and insolubles are avoided wherever possible because of Their detrimenwl effects on mine stability, grade and refining. Sy lvin ite is exTracted by underground mining or brought TO swjace as brine in solution mining. Poiash is separaiedfrom halite byfloiation or sequential crystallization. The refined produci, potassium chloride, is employed as a fertilizer ingredient as well as in chemical and other industrial capaciiies. The ten poiash mines of Wesiern Canada all are in Saskatchewan and account for aboui 25 per cem of world production. Faciliiies are being expanded, and a new mine and refinery was planned for ihe Breden bury area. Deposiis in Manitoba also were being evaluaied.

Jan 1, 1984

By Carlos F. Perucca

"Potassium is one of the three basic plant nutrients along with nitrogen and phosphorus. There is no substitute for potassium compounds in agriculture; they are essential to maintain and expand food production.Potash is extracted from buried ancient evaporites by underground or solution mining. This accounts for most of the potassium produced. Another important source is brine from landlocked water bodies, such as the Dead Sea, Salar de Atacama or Great Salt Lake.About 95% of potash produced worldwide is used in agriculture. The rest is found in several other industrial uses, including glass manufacturing, soaps, plastics and pharmaceuticals.Currently, three producers: IMC, PCS and Agrium operate 8 conventional and two solution mines in Saskatchewan, five of which run froth flotation circuits, two heavy media-flotation, two run forced crystallization and one natural crystallization.Potash in SaskatchewanPotash was discovered in Saskatchewan in the early 1940’s while drilling for oil. The deposits lie diagonally across the southern plains of Saskatchewan sloping southerly from a 1,000m depth at Saskatoon to more than 1,600 m depth at Belle Plaine and up to 3,000 m in depth in North Dakota. The known deposits are massive, accounting for more than 40% of the world’s known reserves."

Jan 1, 2003

By S. Leong

This paper reports on research examining disclosures from mining companies regarding their water usage in the Macquarie and Lachlan catchment areas, both parts of the Murray-Darling Basin in New South Wales, Australia. The objective of the research was to assess whether this disclosure is sufficient to allow communities to determine whether mining companies are complying with mining conditions of consent and abiding by the requirements of their water licencing agreements. These requirements are then compared to the water reporting requirements of the Global Reporting Initiative (GRI) and the Water Accounting Framework for the Minerals Industry (WAFMI). Communities are concerned about whether the mining industry?s use of water will have impacts on their livelihoods and lifestyle and thus require information concerning the quantity of water that will be extracted, how much water will be left for other stakeholders and whether the mining will affect water quality. This is an archival study. It has involved examining relevant publically available information released by mining companies and government regulators and determining if this is sufficient to meet the needs of the local communities. Additionally, it has involved looking at information indirectly provided by mining companies, via the use of intermediaries. Further, information availability concerning basic water accounting and regulatory breeches and whether such information is available at the mine site level has been considered. It is found that while NSW legislation places very little reporting requirements on mining companies, the development consent conditions for new projects and extensions to existing projects are quite significant and should be sufficient to meet the needs of local catchment residents though such information is not always easily accessible for the layperson.

Aug 1, 2013

By I. Campbell, P. C. Jones, E. G. Potter, R. P. Taylor

"The Cobalt embayment is a large domain of Paleoproterozoic clastic sedimentary rocks that unconformably overlies the Archean Abitibi greenstone belt. Regionally extensive sills and dikes of Nipissing diabase, emplaced circa 2219 Ma, occur throughout the embayment and are the preferential host to gold-bearing polymetallic vein systems on the Merico-Ethel property, near the northeastern margin of the Cobalt embayment. These gold-bearing, polymetallic veins are predominantly east-west-trending, steeply dipping, discordant calcite- quartz vein systems that formed close to the time of crystallization (within ~15 m.y., based on Pb-Pb ages) of the Nipissing diabase. The ore mineralogy is complex in character, typically comprising sulfides, arsenides, native metals (gold and silver), and specular hematite, preferentially concentrated along the interface between silicate and calcite gangue. A simplified sequence of mineral deposition in the veins is: (1) "Early-stage" pyrite ± chalcopyrite hosted in quartz ± chlorite gangue; (2) "Main-stage" polymetallic (Cu + Co + As + Ag + Au + Bi ± Pb ± Ni ± U) sulfides, arsenides, and native metals hosted in calcite gangue; and (3) "Late-stage" calcite flooding ± galena. Wall-rock alteration in Nipissing diabase is restricted to narrow (<5 cm) haloes of calcite-chloriteepidote- bearing assemblages, whereas a weak alteration halo of specular hematite, calcite, and allanite-epidote has been observed in the surrounding sedimentary rocks. In terms of their age, geology, mineralogy, paragenesis, and morphology, the gold-bearing vein systems at Merico-Ethel closely resemble the silver-sulfarsenide vein deposits of the historic Cobalt and Gowganda mining camps. These observations indicate that the Au-bearing veins are variants of the Ag-vein systems and as such, have a common genesis belt. L’Échancrure de Cobalt est un large domaine de roches sédimentaires clastiques d’âge Paléoprotérozoïque qui reposent en discordance sur la ceinture de roches vertes d’Abitibi d’âge Archéen. La Diabase de Nipissing, mise en place vers 2219 Ma et qui constitue un réseau de sills et de dykes d’importance régionale, est présente dans l’ensemble de l’échancrure et constitue la roche-hôte principale des systèmes de veines aurifères-polymétalliques de la propriété Merico-Ethel, près de la bordure nord-est de l’Échancrure de Cobalt. Ces veines à minéralisation aurifère et polymétallique constituent un système de veines de calcite-quartz sécantes d’orientation principalement est-ouest et à pendage fort qui se sont formées peu de temps après la cristallisation de la Diabase de Nipissing (à ~15 Ma près, d’après les âges Pb-Pb). La minéralogie de la minéralisation est complexe; elle consiste typiquement en sulfures, en arséniures, en métaux natifs (or et argent) et en hématite spéculaire, préférentiellement concentrés à l’interface entre les silicates et la gangue de calcite. La séquence de déposition simplifiée des minéraux dans les veines est : (1) «Stade précoce» pyrite ± chalcopyrite encaissés dans une gangue de quartz ± chlorite; (2) "Stade principal" sulfures polymétalliques (Cu + Co + As + Ag + Au + Bi ± Pb ± Ni ± U), arséniures, et métaux natifs dans une gangue de calcite; et (3) "Stade tardif" calcite massive ± galène. L’altération pénétrative de la Diabase de Nipissing est confinée à des halos étroits (<5 cm) présentant des assemblages marquées par la présence de calcite-chlorite-épidote, tandis qu’un faible halo d’altération en hématite spéculaire, calcite et en allanite-épidote est noté dans les roches sédimentaires environnantes. De par leur âge, leur géologie, leur minéralogie leur paragenèse et leur morphologie, les systèmes de veines aurifères de Merico-Ethel ressemblent beaucoup aux gîtes filoniens d’argent-sulfoarséniures des camps miniers historiques de Cobalt et de Gowganda. Ces observations indiquent que ces veines aurifères constituent une variante des systèmes des veines argentifères et qu’elles partagent"

Jan 1, 2009

By T. Holmes, J. Middlemiss

"Agnico-Eagle (AE) has been operating their Kittila Mine in Northern Finland since 2008. The mine has experienced considerable ore flow problems with ratholing, bridging and freezing in their mill feed bin since start up. In the first winter of operation, the entire central portion of the contents of the cylindrical flat-bottomed 2000 tonne mill feed bin froze. Flow was erratic and could only be achieved through small diameter ratholes. To maintain a reasonable, albeit limited, feed to the mill, the bin had to be kept less than ½ full and a portable steam generator was brought in to melt the frozen agglomerates that frequently blocked the outlets. The combination of limited surge capacity and frequent outages required the crushing plant to operate 24/7 and resulted in inconsistent production levels and high operating costs.AE had planned to expand the processing plant to increase throughput by about 30% when they transitioned from open pit to underground ore. These plans presented an opportunity to improve the material handling.To avoid the problems experienced with the original mill feed bin, AE enlisted Jenike & Johanson Ltd. (J&J) to test samples of the ore, and based on the measured flow properties to provide design recommendations to ensure that the new mill feed bin would operate reliably. The new 2000 tonne expanded flow mill feed bin and apron feeder were installed in 2014 and are now supplying almost 93% of the total mill feed with the remaining coming from the original bin.IntroductionIn early 2009, AE engaged J&J to visit their then recently opened Kittila mine and mill in Northern Finland (Figure 1). Over the first half-year of operation, production had been restricted in the ore handling and storage system by flow problems such as ratholing, bridging and freezing including blockages of chutes and hoppers as a result of frozen fines buildup and large frozen agglomerates. AE wanted to increase production in the existing open pit mine and mill feed operation and also wanted to avoid similar ore handling problems when they commissioned the new underground mining system under development at that time."

Jan 1, 2017

By F. K. McKean

THE task of establishing a new corrosion testing laboratory is more difficult than it need be because there is very little information on the subject available in the literature. Many articles describing tests and results may be found, but a wide search will unearth only passing remarks on the different types of equipment that may be selected for accelerated corrosion tests. An article describing some of the apparatus needed in a corrosion laboratory should be of help to those interested in building a new unit or in making additions to an old one. In May of this year, the writer was given the assignment of equipping a laboratory for general corrosion testing, to form a part of the new Physical Metallurgy Research Laboratories of the Department of Mines and Resource~ at Ottawa. With the help of senior members of the staff, along with what could be gathered from other sources, a list of necessary equipment was compiled and a plan for arranging it in the rooms was decided upon. Where possible, the apparatus was constructed in the excellent machine shops at the disposal of this Department, while the rest was placed on order with the manufacturers.

Jan 1, 1945

By Shahram Tafazoli

This article presents a novel technology for sensing the size of rocks after blasting in hard rock mines. Blast engineers require rock size statistics to carefully adjust the blasting parameters. The rock fragmentation requirements vary depending on the ore type and crusher specifications. The most popular statistical parameters in the industry are the so-called P numbers (e.g., P80 and P100). A machine vision based system is introduced here for automatic image collection and fragmentation analysis of the material right inside the bucket or dipper of mining shovels. A heavy-duty camera provides the required imaging data to an embedded computer mounted inside the cab. A custom machine vision software continuously analyzes the captured bucket images and stores the suitable ones in local storage which are then fed to a Desktop software for automatic fragmentation analysis. This technology has been developed by Motion Metrics International and is commercially available as FragMetrics?.

May 1, 2009

By Barton G. Stone

The mining and exploration industries have been using Geostatistics (Matheron, 1963) for the past forty years. It has been extensively incorporated into three dimensional block modeling software whose usage has reflected the growth in the use of personal computers since 1980. Because of the utility of geostatistical models in mining and production planning, much of the modern reserve and resource modeling is done by mining engineers, geostatisticians and geological engineers. Explorationists are initially less concerned with three dimensional models until such time as a deposit has been roughly delineated. However, the concept of regionalized variables in ore deposits deals with the effect of spatial correlations between data points in a three dimensional sample space and should be useful for optimizing the spacing of drill holes to allow maximum bang-for-the-buck in drilling programs. This paper examines three common deposit types (porphyry copper, VMS and intrusive gold) to examine whether geostatistical methods have been used to minimize drilling costs because of better understanding of spatial correlations. The three model types were chosen from publicly available corporate websites of Canadian based Junior Mining Companies. They include the Wolverine polymetallic zinc deposit of Yukon Zinc in Yukon, Canada; the El Morro Deposit in Chile (30 percent ownership by New Gold Mining Company, and the Fort Knox Gold deposit in Alaska and 50 percent ownership by Nova Gold Resources). Typically, individual mining corporations post their technical reports as CNI 43-101 reports on their corporate website as indications of the favorability or progress on their more exciting properties. Data considered for this paper was not collected or generated by the author, but the information was extracted from these publicly available sites and had a variety of authorship.

Oct 1, 2009

By K. G. Wheeland, J. E. Dutrizac, M. Wasserlauf, A. A. Condy

Numerous processes for the treatment of thiosalts in base metal milling effluents have been examined in the past decade. Flowsheets for thirteen processes are outlined, and cost estimates are presented for a base case of a 720 mi/h effluent flow containing 1400 mg/L thiosalts. The processes are ranked on the basis of Numerous processes for the treatment of thiosalts in base metal milling effluents have been examined in the past decade. Flowsheets for thirteen processes are outlined, and cost estimates are presented for a base case of a 720 mi/h effluent flow containing 1400 mg/L thiosalts. The processes are ranked on the basis of

Jan 1, 1988

By S. Chung

Mining in highly stressed ground conditions has been an increasing challenge at the Brunswick mine. Over the past 30 years, two large regional pillars were established on the 1000 m Level to support the ground for safe extraction of the surrounding ore. The South Regional Pillar contains about 5 Mt of ore and the North Regional Pillar has about 3 Mt of ore. In the fall of 2000, mining activities were suspended following a series of ground movements around the South Regional Pillar along weak geological structures. After extensive geotechnical investigations, a decision was made to carry out a mass de-stress blast in the West Ore Zone (WOZ) to cut the principal stress across an area of 135 m along strike and 86 m high. At the end of July 2001, the WOZ mass blast was successfully initiated. Following this success, the mine decided to take a similar approach to de-stressing the North Regional Pillar (NRP). The final mass blast was taken in early February 2003. Advanced blasting technologies, including state-of-the-art electronic detonators and blast simulation, played an important role in achieving the successful blasts. The high precision of delay timing and long delay duration of the electronic detonators ensured accurate and reliable initiations of over 800 blastholes in the WOZ mass blast. Orica’s DMC_Blast (Distinct Motion Code) simulation code was used to study different blasting blocks for the desired timing in the initiation sequence. This paper describes the process of applying electronic detonators in complex blasts, and discusses how blast simulation results were interpreted to guide engineering design of the mass blasts.

Jan 1, 2005

By A. R. Khodabandeh, T. Nematkhah

Correct selection of forging parameters is very important to produce sound superalloy parts. In this investigation nickel-iron base superalloy IN901 successfully forged and seal spacer, which is a part of airplane with about 11 kg weight has been produced. Forging has been performed on the basis of hot compression results, which show deformation above 1100°C associated with dynamic recrystallization (DRX) which can increase the workability of material. On the other hand annealing at 1100°C decreases the flow stress during hot compression, and then increases the material formability. Then billets annealed at 1100°C in electrical furnace for 24 hours and reheated again to 1100°C before forging. Initial square cross section billet with 128mm side and 202mm length forged immediately after reheating by 80MN mechanical press. Specimens forged in five steps: upsetting, three steps molding and finishing. Preformed and molded specimens reheated in electrical furnace before later step of forming. Finally specimens trimmed by 1 OMn mechanical press and hot set by hydraulic press and then cooled in air to room temperature. Results show that reheating temperatures has been selected correctly because there isn&apos;t any surface crack and die cavities filled completely by forging material. Material flow has been carried out properly and there isn&apos;t any defect in critical points especially in extradoses and intradoses. Microstructural examinations show that grain boundaries contain Ti-rich globular particles that formed during cooling.

Jan 1, 2006

By M. L. Joy

The heat pipe is a self-contained, passive structure that uses a liquid-vapour fluid cycle to provide high thermal conductance . Through the proper selection of working fluids and container materials, heat pipes have been operated at temperatures ranging from less than -300°F to more than 3,000 °F. The passive nature, high efficiency and configuration flexibility of the heat pipe are presented. The application of McDonnell Douglas Astronautics Company Cryo-Anchor® heat pipes for foundation and support stabilization in permafrost regions is discussed. Using the proven Cryo-Anchor technology base. a proposed application of heat pipes in a cold -region mine ventilation system heat recovery heat exchanger is presented. Information obtained from the development of an air-cooled heat pipe steam condenser provides the technical basis for large -scale heat pipe applications.

Jan 1, 1978

By P. Scinto, A. Festa

"Orway Mineral Consultants Ltd (OMC) as a consultancy has specialized in comminution circuit design for over 30 years. The OMC Power Model is OMC’s in-house software for specific grinding energy power-based circuit calculations. The model uses ore hardness parameters from testwork, circuit configuration, equipment geometry and operating conditions as inputs. The model combines proprietary and published power models to predict the total specific energy and the specific energy for each of the components of the comminution circuit. This makes the software a valuable tool for the design and validation of JKSimMet modelling or actual plant performance. Proprietary calculations have been developed and reconciled with over 100 plant benchmark projects encompassing a variety of comminution circuit configurations.This paper describes the OMC approach for determining power requirements for the design of grinding circuits. The accuracy of the OMC Power Model software is confirmed through plant survey benchmark performance and comparisons are made with other power modelling techniques. Practical examples are presented, showing applications for single stage SAG (SS-SAG), SAB and SABC circuit configurations.IntroductionConventional low throughput grinding options, consisting of multi-stage crushing followed by rod and ball mills, have almost become obsolete in the move to higher milling rates required to process lower metal grades. Grinding circuits with fully autogenous (AG) or semi-autogenous (SAG) mills, often combined with ball mills are now the standard to meet the high capacity requirement for processing ores with lower metal grades. Simulation software and power-based equation methodologies have been established for designing AG/SAG based grinding circuits and predicting their energy requirements.Presently, power-based equations remain the principal method for designers to size mills and estimate the power requirement for comminution circuits. The technique is simple and it relies on the design to specify a feed and product size plus a hardness index to produce a specific energy value (kWh/t). The desired throughput of the mill is multiplied by the specific energy to give the mill power requirement, which is used in turn to size a mill for dimensions, internal geometry and loading conditions to match the power draw."

Jan 1, 2015

By A. Mitura

The paper presents the initial investigation of possible energetic applications of chosen wastes from groups: 06, 03, 05 and 01, including coal slimes being secondary product of hard coal processing. These categories of wastes are catalogued according to the polish law, where 06 ? wastes from production, preparation, purchasing and application of products of non-organic chemistry; 03 ? wastes from wood processing and from plates and furniture, celluloid mass, paper and card board production; 13 ? oil wastes and wastes from liquid fuels; 01 ? wastes produced by searching, extracting, physical and chemical processing of ores and other mineral raw materials. The change of combustion heat value was evaluated in produced energetic mixtures containing these types of wastes together with the change of their individual components. All combinations of ingredients were taken into consideration giving 256 various mixtures, from which 36 were selected to investigation. This allowed the performance of statistical factor analysis. For such prepared materials the application of regressive method was proposed in purpose of calculating combustion heat value and then the comparison of empirically determined and theoretically calculated heat values was performed. The change of regressive coefficients can be determined by the nature of Hess law (eq. 1) what was investigated and the attempt of its explication and validation was done.

Aug 1, 2013