Search Documents

By Deni Lessard, Roger Demers, Noël R. Billette

"The Quebec Mining Association has for many years been supportive of the activities of the Centre de recherches minérales which were initiated to ensure regular production hoist and cable inspections to maintain safety and productivity standards in underground mines in Quebec. CRM and CANMET have agreed to fund a Quebec Mineral Development Agreement contract to capture this accumulated knowledge. Using VP-EXPERT to process the information and subdirectories to store regulations, the prototype access D-BASE III records on hoist information and LOTUS 123for simulating working conditions that meet local regulations and expert rules of thumb criteria. Objectives are to improve safety in emergency operating procedures, maximize hoist productivity and safety, and promote knowledge transfer to operators."

Jan 1, 1992

By I. Perus, M. Fazarinc, G. Kugler, M. Tercelj

"Ledeburitic tool steels are highly alloyed steels used for specific highly loaded applications but are characterized by low and variable hot workability. In this contribution the importance of selecting the right choice of some essential process parameters, i.e. casting temperature, solidification rate and soaking temperature, needed for improving the intrinsic hot deformability of ledeburitic tool steels, is studied. An inappropriate selection of casting temperature and cooling rate results in precipitation of unusual eutectic carbides that decreases the hot workability, whereas with the selection of appropriate soaking temperature the temperature range of safe hot working can be broadened. For each initial as-cast microstructure individually determined soaking temperature should be selected.IntroductionThe surface cracking during hot deformation of ledeburitic tool steels reduces mechanical properties and their industrial yield. These tool steels have high hardness, wear resistance and high tempering resistance on one hand, and high flow stresses and low hot deformability on the other. Decreased hot deformability of the tool steels is attributed to the type, size, shape, distribution, fraction of eutectic carbides and/or other phases, grain growth, etc. at upper limit while precipitation of secondary carbides and decreased recrystallization rate at lower limit of the safe hot deformation temperature range, [1-6].The occurrence of cracks on most exposed areas of workpiece are related to the areas where similar conditions related to upper and/or lower limit of temperature working range prevail, i.e. areas with accelerated cooling, areas with higher value of accumulated strains where also decreased recrystallization rate with simultaneously presence of higher tensile stresses takes place, furthermore areas of workpiece which are due to combustion conditions in furnace heated to higher temperatures, etc. Thus the areas, where combination of previously mentioned conditions prevails, are more exposed to cracking. This additionally requires that hot deformability of ledeburitic tool steel should be considered as a complex problem. Publications in the literature with regards to hot deformability of tool steels are predominately of a partial nature thus all reasons for unexpected occurrence of cracks are not sufficiently explained in available literature so far. Furthermore modern practice proves that previous processing parameters significantly influence the hot deformability and thus this cannot be considered as a constant value. During heating, soaking and hot deformation various processes take place: decay (decomposition) of carbides, formation of new carbides, dissolution of carbides and of alloying elements, etc. Thus depending on variation of process parameters and chemical composition, that consequently influences the processes related to carbides, shifting of decreased deformability at both limits of temperature working range to higher and/or to lower temperatures can occur, [1-14]."

Jan 1, 2012

By B. Zhu, W. E. Lee, N. Li

Al powder is used extensively as an antioxidant in carbon-containing bricks, but it cannot be used directly in water-based carbon-containing castables due to its hydration tendency. To overcome this problem, in this work, SiO2-PVA (polyvinyl alcohol) inorganic-organic hybrid coatings have been prepared via sol-gel processing, and used to coat Al powder. The hydration behaviour of uncoated and coated Al powders has been investigated in water at 60 or 100°C for 36h by examining phase and microstructural changes. While significant hydration is detected in uncoated Al powder, no obvious hydration is detected in coated Al powder, indicating that its hydration resistance has been greatly improved. Oxidation resistance of graphite coexisting with uncoated or coated Al powder was also investigated in air at 1250°C for 1.5h. The oxidation ratio of graphite coexisting with coated Al powder was similar to that of graphite coexisting with uncoated Al powder, indicating that both powders showed similar antioxidising behaviour. This, along with the much improved hydration resistance, makes the coated Al powder a potential antioxidant in carbon-containing castables systems.

Jan 1, 2004

Now you know why there is concern about mine illumination. You have some idea about how the human eye works and about the problems of glare, peripheral vision, and accommodation. And you know that lighting in a mine presents special problems because of the dark surroundings and low reflectance. This chapter describes what can be done to improve conditions. This chapter begins with a short discussion about Federal Standards on mine lighting -- what they are and what is being done to carry them out. The chapter then describes different types of lamps that can be used for mine lighting, and discusses their advantages and disadvantages. Finally, the chapter lists some things that you can do personally to improve lighting, or can point out to others so that improvements can be made. The Federal Government is doing its part to improve mine lighting by establishing regulations. Lamp manufacturers are constantly studying new lamps to provide better equipment. And your company will do its part to comply with regulations. Better lights may not be here yet, but they will be soon. But in the end, you are the one who will be using the lights, and you are in the best position to see the improvements. You are also in the best position to see and tell others where further improve¬ments can be made.

Jan 1, 1976

A novel, low-pressure adaptation of Praxair?s coherent jet technology utilizing CoJet lances was developed for application at Inco&apos;s Copper Cliff Smelter where oxygen is available in large tonnage quantities but only at relatively low supply pressures (< 193 kPa header pressure). The project objectives were to evaluate the effect of coherent jet technology on controlling oxygen lance accretion (?horn?) formation and to increase oxygen efficiency in the Inco Oxygen Top-Blowing Nitrogen Bottom Stirring (TBBS) MK Reactor used for converting nickel- contaminated chalcocite to semi-blister copper. This paper describes the development and subsequent implementation and testing of two CoJet lances in this application.

Jan 1, 2005

By M. Rafiee

Indoor physical security, as a perpetual and multi-layered phenomenon, is a timeintensive and labor-consuming task. Various technologies have been leveraged to develop automatic access control, intrusion detection, or video monitoring systems. Video surveillance has been significantly enhanced by the advent of Pan-Tilt-Zoom (PTZ) cameras and advanced video processing, which together enable effective monitoring and recording. The development of ubiquitous object identification and tracking technologies provide the opportunity to accomplish automatic access control and tracking. Intrusion detection has also become possible through deploying networks of motion sensors for alerting about abnormal behaviors. However, each of the above-mentioned technologies has its own limitations. This paper presents a fully automated indoor security solution that leverages an Ultra-wideband (UWB) Real-Time Locating System (RTLS), PTZ surveillance cameras and a Building Information Model (BIM) as three sources of environmental data. Providing authorized persons with UWB tags, unauthorized intruders are distinguished as the mismatch observed between the detected tag owners and the persons detected in the video, and intrusion alert is generated. PTZ cameras allow for wide-area monitoring and motion-based recording. Furthermore, the BIM is used for space modeling and mapping the locations of intruders in the building. Fusing UWB tracking, video and spatial data can automate the entire security procedure from access control to intrusion alerting and behavior monitoring. Other benefits of the proposed method include higher accuracy and robustness, more complex query processing, and interoperability with other BIM-based solutions. A prototype system is implemented that demonstrates the feasibility of the proposed method.

Aug 1, 2013

By G R. F Alvear Flores

Mineral resources are becoming more complex in composition and structure making it more difficult to produce clean concentrates for primary metal smelting. In parallel, providing technological solutions to the recycling and recovery of end-of-life materials is becoming more important in moving towards the goal of increasing circularity. The availability of fundamental thermodynamic data and advanced thermodynamic tools greatly assists in evaluating these complexities and their impact on existing and new processes. In addition, it is fundamental to support the economic performance of smelters. This paper describes several examples on how fundamental work can be applied to industrial processing..

Jun 17, 2024

By N. du Preez, J. Christie, F. Crundwell

Precipitation is a key process in the recovery of copper and cobalt. While there is a wealth of experience in operating precipitation steps, improving their performance remains challenging. Chemically, the reaction might be controlled by reaction kinetics, be limited by oxygen mass transfer, or be at equilibrium. In this paper, we examine these different operating regimes and demonstrate how they can be identified from plant operating data, process modelling, and pilot plant test work

Jan 1, 2023

By J. M. Ekenes

New approaches that increase hydrometallurgical recovery from refractory minerals in below-mill-cut-off-grade sulfide copper ore can add significant value, improve profitability and increase ore reserves. This paper describes the development and implementation of an engineered heap (EH) approach to leaching low-grade, chalcopyrite-bearing ore at Freeport-McMoRan?s mine in Morenci, Arizona. The technical evolution of the engineered heap concept is described together with the challenges and benefits following implementation.

Jan 1, 2012

By J. M. Ekenes, C. A. Caro

"New approaches that increase hydrometallurgical recovery from refractory minerals in below mill cutoff -grade sulfide copper ore can add significant value, improve profitability and increase ore reserves. This paper describes the development and implementation of an engineered heap (EH) approach to leaching low-grade, chalcopyritebearing ore at Freeport-McMoRan’s mine in Morenci, AZ. The technical evolution of the engineered heap concept is described together with the challenges and benefits following implementation. Introduction The Morenci ore deposit, located in eastern Arizona, has been mined for copper for 140 years. Mineralization in the Morenci district consists of sulfides and oxides. To process these ores, Morenci operates concentrator and leaching circuits. Leaching accounts for two-thirds of the copper produced in Morenci. More than one-half of this leaching-derived copper production comes from run-of-mine (ROM) stockpiles. The largest category of material moved in Morenci is destined for ROM stockpiles and waste dumps. Materials that are not economic to mill or leach are designated “waste.” However, this designation can change based on improvements in extraction technology and commodity prices. Chalcopyrite does not leach well due to its refractory nature. For predominant chalcopyrite mineralized ore, copper recovery during a typical leaching cycle may be as low as 5%. For this reason, chalcopyritedominant ores below mill cutoff grade have historically been classified as waste. By incorporating advanced leaching technology to improve metal recovery from previously leach-resistant ore types such as chalcopyrite, the Morenci Mine has been able to reclassify substantial amounts of this “waste” to “ore.” Process chemistry Chalcopyrite copper extraction is temperature, oxygen and ferric dependent. The temperature is achieved primarily by pyrite oxidation (Eq. (1)) and secondarily by oxidation of chalcopyrite itself (Eq. (2)). The regeneration of ferric in solution can be enhanced by providing the appropriate acid and oxygen levels according to Eq. (3). In the absence of microorganisms, this reaction is very slow."

Jan 1, 2015

Drilling and blasting operations have historically been viewed as a necessary &apos;evil&apos; part of mining, whose costs should be minimised by whatever means possible. In the past, when operations depended primarily on crushing and milling for ore re

Jan 1, 1998

By Alan D. Akerman

This paper describes the significant advantages and improvements in operational availability, reduced breakdowns, and overall cost reductions that can be achieved through the application of a Reliability Centred Maintenance (RCM) program, including Condition Based Maintenance (CBM) and Equipment Health Monitoring (EHM), in a mine environment. It uses a case study to illustrate the essential elements that constitute the basic requirements to establish such programs. This CBM case study analyzed the Load-Haul- Dump (LHD) vehicle sub-systems and their dominant failure modes, as a precursor to the development of condition indicators. The case study describes a disciplined process to enable condition indicator development and qualification in support of a CBM program. The identified condition indicators vary from readily applicable off-the-shelf monitoring systems and techniques, through to "leading edge" technologies that require further research and development. The paper also explores the developments that have been made in the combination of expert system software associated with modern computer based control systems, and the availability of "intelligent? sensor technology that complement the control system capability.

May 1, 2002

By S. J. Ripke

To pelletize fine moist magnetite concentrate, a 40% water slurry must be dewatered to about 10% by filtration, before it can be agglomerated into pellets. Slurry pH, typically ranging from 8 to 11, gives the magnetite particle surface a strong negative charge and thus causes two adverse effects. First, this negative charge attracts calcium and magnesium cations, which strongly retard the effectiveness of the bentonite clay binder added during agglomeration. Second, a repulsive force created by the negative charge functions as a dispersant that reduces filtering production rates. Tests were conducted to remove these cations during filtration, by rinsing the moisture remaining in the filter cake with a small amount of water adjusted to pH 6 with HCl. Laboratory work was also conducted at Michigan Technological University (MTU) and at Cliff’s Mining Services Company (CMSC) to corroborate the plant tests. In some cases HCl caused filter bag blinding, therefore CO2was investigated to reduce pH. The CMSC lab tests showed that using carbon dioxide to reduce slurry pH from 7.6 to 7.0 improved filtering production rates by 11%. Plant-scale filtering rates were improved by 23.7% when carbon dioxide addition reduced the slurry pH from 8.6 to 6.7.

Jan 1, 2004

By John Crusius

? 3-year research program overview ? initial results- MainZone pit Waterline pit ? questions raised ? increasingly common in western N. America ? frequently low-pH waters with elevated concentrations of many metals ? water quality controls poorly understood ? some in U.S. are Superfund sites

May 1, 2002

By A. Elsayed

Lightweight metals such as magnesium show potential in replacing aluminum alloy castings for engine cradles, cylinder heads and transmission cases. Unfortunately, magnesium alloys are susceptible to entrapping oxides and other impurities during casting that hinder strength and ductility. The current study examined various filter sizes and configurations with the aim of improving the mechanical properties of permanent mould cast AZ91E. The unfiltered casting had a yield strength, tensile strength and ductility of 93.3 MPa, 153.3 MPa and 2.2 % respectively and increased to 96.5 MPa, 167.0 MPa and 3.1 % with the use of a fine mesh filter within the well of the mould. The increased strength and ductility was likely due to the filtered castings containing fewer inclusions on their fracture surfaces as compared to the unfiltered castings.

Jan 1, 2011

By K. Narayana Swamy

The traditional approach to improving the operating efficiency of a metallurgical plant has been to study individual unit operations and focus on improving the poor-performing unit operations. The complex nature of most metallurgical plants call for a holistic approach that will consider the whole rather than just focus on the individual units of a plant. This holistic approach is part of the systems thinking principles. Numerous case studies highlight the importance of the need to apply systems thinking principles in improving the effectiveness of metallurgical operations. Improving the efficiency of one unit operation without considering its effect on the performance of other unit operations has in many cases lead to lower overall operational efficiency. Modeling and simulation are key to the application of the systems thinking principles. Standard flowsheet models are very useful in scenario analyses though they have to be supplemented with other models for useful predictions.

Jan 1, 2006

By Osvaldo A. Bascur

Industrial complexes rely on measurements of flow rates, qualities, and concentrations for monitoring and optimizing their operation. Corporations use the data from the various sensors and measurements to make business decisions, which affect the profitability of the operation. However, gross errors, due to a variety of reasons like faulty sensors, bad instrument calibration, or incorrect process models may corrupt the actionable information supplied to operations, quality managers, and maintenance personnel. The solution is to use the sophisticated new tools to model the process, sift through the available data to locate the gross errors, and use statistical data reconciliation to validate the sensors and instruments. In this way the data are unified to give the most accurate plant information for use by the monitoring and decision making processes. Most mining and metallurgical plants use predictive maintenance policies based on statistical analysis and special techniques, like vibration analysis, and oil and lube analysis for critical equipment. Process control strategies are installed in several metallurgical sites. All of these depend on reliable and accurate data. The data unification methods validate the individual measurements by using the concept of balances and statistical techniques where each instrument is no longer independent of the other measurements in the facility. This paper refers to the data unification and analysis methods required for profitable plant operations. Continuous improvement and monitoring of the measurement system at the plant and analysis of the reconciled data provide the best information for the decision-making process. On-line gross error detection and elimination methods are required to ensure efficient evaluation of process performance and process optimization. An open discussion of the new methods for gross error detection and data unification will be presented.

May 1, 2001

By Pat Turner, Abrie Schutte, Tim Olson, Roman van Ommen

The key to good cyclone circuit design and operation in primary grinding circuits will be discussed. Cyclone circuit design issues include individual cyclone design features such as cone angle or materials of construction, as well as orientation and manifold configuration. Cyclone performance issues as well as maintenance considerations will be detailed in an effort to achieve consistent cyclone operation with minimal coarse solids in the overflow. The new gMAXTM. cyclones will be introduced and evaluated using operating circuit data in closed circuit grinding applications

Jan 1, 2003

By Patrick A. Turner, Timothy J. Olson, Abraham J. Schutte, Roman van Ommen

"The use of classifying devices in grinding circuits dates back to the early 1900’s when classifiers were installed to close ball mills. The search for ways to further improve grinding circuits led to the use of hydrocyclones in place of mechanical classifiers in South Africa in the early 1950’s. Today Hydrocyclones are considered as the best classifying devices to close grinding circuits. After 50 years of development the hydrocyclone has changed significantly when compared to the designs of the early days, but the focus to circuit optimization must be expanded to an understanding of the integral system consisting of mill, cyclone feed pump and cyclone.The key to good cyclone circuit design and operation in primary grinding circuits will be discussed including individual cyclone design features such as cone angle or materials of construction, as well as orientation and manifold configuration.Cyclone performance issues as well as maintenance considerations will be detailed in an effort to achieve consistent cyclone operation with minimal coarse solids in the overflow. “The importance of constant cyclone feed conditions is unquestioned today. The challenge of Cyclone sizing is a large number of not fully known variables prior to startup. The most significant unknown variable is slurry viscosity. Because of this, engineers often specify a conservative cyclone system that produces a finer than required separation. However, this approach often leads to higher circulating loads and a higher overflow density in order to produce the required separation. The higher cyclone overflow density results in a less efficient cyclone separation. The average concentrator can pick up 2-4% finer overall grind by having a more aggressive cyclone operation.”"

Jan 1, 2003

By Osvaldo A. Bascur, J. Pat Kennedy

"The profitability of mining and metallurgical operations continues to lag behind that of other industries despite the technical advances that have occurred in recent years. A primary reason for poor performing in this economic sector is the lack of integration of mining and metallurgical information. The mine cut-off grade can be optimized if mining and metallurgical engineers have the data to optimize milling for the type of ore in hand.Integration of mine transactions, stockpile inventories, process flows and assays is the key to determining the economics for each blast strategy in a mining site. Real-time information from manufacturing assets greatly affects the profitability and flexibility of a company, but gross errors from faulty sensors, inaccurate instrument calibration, or incorrect process models may corrupt actionable information. New software tools can model the process, sift through available data to identify and eliminate gross errors, and use statistical data reconciliation to create materially balanced and consistent readings. The reconciled data is unified for use by both monitoring and decision making processes.Creating a real-time information environment where upgrade and change are allowed is becoming an accepted methodology to accelerate and simplify the integration of applications such as production monitoring, equipment performance management and yield and inventory management."

Jan 1, 2003