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By Robert McClure, Frederic Leclercq, Ricardo Chavez

With significant vibration control and fragmentation challenges facing them, the CBS quarry (department of the Nord) successfully integrated a technical partner and mine to mill optimisation to deal with a difficult environment. For the last three years, CBS has been conducting a global production monitoring program similar to the mine to mill concept used in the mining industry. This concept consists of optimising the drilling and blasting while monitoring the effects on the downstream chain (vibration control, loading, hauling, crushing, plant output). Blast optimization is ensured by systematic control of the blast geometry (volumes, patterns, bench and face anomalies, drill deviation) and by the use of constant specific energy blasting. Constant specific energy optimises the work of the explosive in a blasting operation and, when combined with a high accuracy programmable electronic blasting system, reduces the impact of blasting on the environment and enhances blast performance. These techniques ensure consistent blasting results and hence improved site productivity. The improvements achieved have been identified thanks to an effective system designed to monitor the key production parameters.

Jan 1, 2007

By K. Kavouridis

Coal is broadly recognized as sure, competitive, diversified, not vulnerable and predictable in price energy resource. In power generation coal is playing a dominant role in the EU-27 with 25% of installed capacity and almost one third of the power generation. The role played by the domestic resources and especially by coal are increasingly becoming the focus of the EU energy strategy. There is a strong pressure for the decarbonization of the energy mix. The Emission Trading system (ETs) can have an impact on the shift to lower carbon-intensity fuels. The impact of ETs on coal can be important, because it is very short sighted and only defines the period up to 2008-2012. The ETs CO2 regime must ensure that investment in coal-fired plants in the long term are supported. EU Research Institutes and Coal Industry identified an important CO2 reduction potential by improving the efficiency of the conversion of solid fuels into electricity. Highly efficient clean coal technologies can contribute to reasonable costs and challenge the issue of climate change. It must be pointed out that the EU Energy policy should now concentrate on the necessity to effectively support demonstration projects and to create the legal framework for the integrated approach of efficiency enhancement and CCS. It is not a right approach to implement CCS before the technology is demonstrated and before it is clear that it will be commercially viable.

Jan 1, 2007

By R Ashworth, S J. Hall

During trials which began in May 2005, traditional steel dump bodies for transporting iron ore on 220-tonne haul trucks at a Labrador iron ore mine were compared to a novel rubber suspended dump body. Loads were measured and compared over some 93 700 loads, representing more than 20 Mt transported. Maintenance costs and downtime were also measured over the course of the trial, which lasted nearly one year. This paper outlines the parameters and results of the trials. Parameters measured included payload and production improvements, carry-back reduction, downtime due to body maintenance, and wear on the floor of the suspended dump body. These parameters were then compared to those for conventional steel dump bodies in use at the mine, and conclusions were drawn. The resulting comparisons were significantly positive in favour of the new suspended dump bodies, confirming that each truck could haul an additional 41 000 tonnes per year, that downtime hours could be considerably reduced, and that body availability and service life can be extended through use of the suspended dump body. There was also a high level of operator acceptance of the suspended dump bodies due to less loading shock and a smoother ride.

Jan 1, 2007

By V K. Singh, G Sural

The problem of spontaneous heating/fire is very common in coal mines all over the world. The coal industry faces many problems day by day due to the occurrence of spontaneous heating in the open pit coal mines. Presently, about 70 per cent of total coal production in Indian mines is being carried out by open pit mining. Fire in coal, particularly in open pit mines not only causes irreparable loss of natural wealth but also damages the surface structures and pollutes the environment. It is well known that 75 per cent of the fires occur due to the spontaneous combustion of coal. Spontaneous heating is a very common occurrence in coal mines and is a major factor contributing to mine fire. The liability of coal to spontaneous heating causes many serious problems before, during and after mining. In opencast mines, coal immediately oxidises and catches fire due to the intrinsic characteristics of coal, such as low rank, high moisture, high volatile matter, presence of sulfur in the form of pyrites, low crossing point temperature (CPT) and ignition point temperature (IPT) value and less incubation period. In opencast mines, when the coal benches are left idle for a longer time, heat accumulation takes place in favourable conditions and sometimes leads to fire. The purpose of this paper is to present the different successful case studies regarding the safety management of open pit coal mines from occurrences of spontaneous heating/fire.

Jan 1, 2007

By N. Fukatsu

The recent development of galvanic cell-type hydrogen sensor for molten copper was outlined. The principle of the sensing mechanism, the fundamental structure of the sensor, and its performance as a process control device are discussed based on experimental work undertaken by the authors. Besides sensors based on usual perovskite-type proton conducting oxide, those using magnesium-doped alpha alumina, which was recently known as a proton conductor, were investigated and the results at the laboratory scale are reported. Considering the excellent sensitivity at high temperature and the stability to the disturbance from the attendant oxygen activity, magnesium-doped alpha alumina was regarded to be a superior material for the sensors used for such purposes.

Jan 1, 2007

By N. Wachgama, J. P. T. Kapusta, R. U. Pagador

The Thai Copper Industries smelter (Thai Copper) is located some 200 km southeast of Bangkok near the MapTaPhut deep sea port in one of the industrial centres of Thailand. Although construction of the complex started in the mid 1990s, the smelter, acid plant and refinery were completed in 2004. Thai Copper is a state-of-the-art copper smelter processing imported concentrates with a total yearly capacity of 165,000 tonnes of cathodes. It employs the El Teniente Technology where concentrates are blended and smelted continuously in a primary smelting reactor to produce high grade matte or white metal. The white metal is converted in batches to blister copper in Hoboken siphon converters equipped with Air Liquide Shrouded Injector (ALS I) Technology for sonic injection of oxygen enriched air. Final refining is carried out in two anode furnaces prior to anode casting and electrorefining. Thai Copper and Air Liquide Canada executed a technical assistance agreement in late 2005. Pre-commissioning of the shrouded injectors took place in July and November 2006 while hot commissioning occurred in December 2006. This paper presents the major technical aspects of the joint commissioning, including the establishment of operating practices specific to shrouded injection converting. Preliminary results of this first commercial implementation of ALSI Technology in copper converting are also provided.

Jan 1, 2007

By Richard Peaker, Jens Lichter, Alexander V. Potapov

"The recent combination of Computational Fluid Dynamics (CFD) and Discrete Element Modeling (DEM) can provide considerable insight into the performance of flotation cells. One area of interest from a fundamental equipment design perspective has been the influence of flotation cell size and the inflow rate on the metallurgical performance of the cell. One of the specific design objectives when increasing the size of flotation cells, or increasing the feed flow to the flotation cell, is to ensure that the feed stream flowing into the cell does not have an opportunity to bypass the mechanism.This paper describes the initial modeling efforts to quantify the inter-relationship of cell size, inflow rates, and feed and discharge box placement, on the retention time distribution of solids in the flotation cell, and the fraction of particles that bypass the mechanism on a size by size basis.INTRODUCTIONThe great majority of newly installed cells in mineral processing plants world-wide are of the cylindrical tank design and this tank shape offers a number of hydraulic advantages over the older style of square cells. Cylindrical cells give symmetrical flow patterns and by careful design of the mechanism and tank internals, the flow patterns generated can concentrate the more intense mixing in the lower portion of the cell to promote good solids suspension and particlebubble contact. Simultaneously, cylindrical tank design gives a more quiescent upper zone for particle-bubble transport into the froth zone. These symmetrical flow patterns are naturally disturbed in normal operation by the slurry inflow and outflow from the individual cells. The challenge for flotation cell designers is to determine the magnitude of these flow disturbances, and to assess whether or when the inflow and outflow rates have a sufficient impact on the hydraulic flow patterns so as to potentially affect the metallurgical performance of the flotation cell."

Jan 1, 2007

By C. A. Rawlins

Deep underground mines use refrigeration systems to provide a reasonably comfortable ambient environment to increase productivity and to maintain safety as a priority. Deep level gold mines maintain the environment at an acceptable temperature, i.e. 27°C. However, the increasing cost of doing so through refrigeration is becoming a significant factor in the economic viability of mines. This paper discusses of the important facet of energy losses in cooling reticulation systems, laying with the specific emphasis on the subject of chilled water transport pipe insulation and its thermo-dynamic relationships. Aspects relating to the deterioration of open cell-type insulation materials such as polyurethane/styrene foams and the use of Phenolic resins that have good fire retardation properties have been investigated. The thermal conductivities of these insulation media are good (meaning below 0.05 W/°C)However, they are known to be negatively influenced by water vapour ingress and vapour pressure differences that result in the ingress of water into the material by means of absorption, condensation, hygrospicity, permeability and capillary action, to name a few of many. The overall effect on mine cooling efficiency takes in the two forms: first by the loss of refrigeration or increased chill in the water temperature arriving in a given section and second, by a loss in transfer efficiency when the gap between the arriving water temperature and the actual air temperature decreases. Keywords: Conductivity, vapour, insulation, fluid, thermal, temperature, pressure, transport, refrigeration.

Jan 1, 2007

By Y. G. Che, M. Brown, R. L. Gandhi, M. D. Watson

Slurry pipelines have proven to be an economical method of mineral concentrate transport over long distances. Some of these pipelines are internally lined with high-density polyethylene (HDPE) to avoid internal corrosion. HDPE is an inert and extremely smooth material, and it was believed hat scale deposits would not form on it. However, there have been instances of scaling on HDPE lined pipes. Scale problems have also occurred on bare steel pipes. In this paper experience with scale problems in some of these pipelines will be summarized. Alternatives available for control of scale problems will be discussed, and a success story for the control of scale problems in the 300 km long Century zinc and lead slurry pipeline will be presented.

Jan 1, 2007

By Paul A. Lang

Jan 1, 2007

By V. Matou?ek

The paper addresses pipe flows of aqueous medium-sand slurries at velocities lower than the deposition-limit velocity. Laboratory test results including measurements of particle concentration distributions are used in order to describe a flow with a (pseudo-) linear concentration gradient above a stationary bed. Particle dispersion within the flow is evaluated and a stratification-ratio equation is formulated, estimating a portion of contact load in the flow. The formula is incorporated in the proposed predictive model for the hydraulic gradient for a medium-sand flow above a stationary bed.

Jan 1, 2007

By Francis Kendorski

The mining engineering design professional has limited practical and reliable tools for planning successful room-and-pillar stone mines using readily-available and collectible information. Three techniques are in common use today: the hard rock CANMET method of Hedley and Grant, the hard rock method of Stacey and Page, and the oil shale method of Hardy and Agapito. Other methods have been proposed, such as the USBM method of Obert and Duvall, the CSIR/Penn State method of Bieniawski, and the soft rock confined core method of Abel, Wilson, and Ashwin. However, the latter have practical shortcomings when applied to room-and-pillar stone mines such as developed for construction aggregate production. Ideally, the use of multiple techniques resulting in the same acceptable and reliable answer is the goal. Recently, in several underground stone mines areas of undersized pillars were examined. These undersized pillars apparently resulted from non-adherence to a mine plan. These undersized pillars now exhibit strong evidence of incipient failure such as slabbing, opening of through-going fractures, and hour-glassing. This situation allows examination of pillar designs at a ?safety factor? of essentially one. This rare opportunity allowed the examination of the suitability and adjustment of the first three design methods discussed, resulting in greater overall confidence in the methodologies.

Jan 1, 2007

By G. S. Ospanova

The results of complex processing sulphide copper ore and advantages of recovery of copper by vat and heap leaching, sorption, cementation and electrolytic solutions processing and utilization of waste material after heap leaching of copper for production of building materials were investigated. The combined chemical solvents with the additives of oxidizing agents are developed at the KazNTU. The solvents are inorganic or organic chemical reagents, which form complexes of Cu, Au, Ag, Pt, Ni, Sr, Co etc. Recovery of non-ferrous metals from solutions and purification of industrial waste waters is carried out on the base of using new synthetic and natural sorbents (from local raw materials) which are able to bind ions in both cationic and anionic forms depending on type of ligands and external conditions. Optimum parameters of copper sorption were determined. The developed wasteless technologies of copper extraction from sulphide ores with usage of new non-toxic solvents and accessible sorbents with full recycling of water are tested in pilot scale heap leaching, and are recommended as the ecological, economical and practical alternative to traditional methods.

Jan 1, 2007

By Robert Hopler

In part four, the instrumentation used to detect the vibrations from the 1876 Hell Gate (East River, New York) reef-clearing blast was discussed. The apparatus consisted of cups of mercury and microscopes or other magnifying instruments to detect ripples or waves on the surface of the liquid metal.

Jan 1, 2007

By M. Kreuh

An investigation of the pressure pulse spectrum generated by the gas dispersion processes in a Peirce Smith copper converter was undertaken via the simultaneous measurement of four tuyeres using high frequency pressure transducers. The data was captured, stored, and analyzed using digital data processing techniques; including power spectral density plots, band-pass filtering, and a principal component analysis (PCA). The process was characterized throughout by a dominant 3 Hz pulse signature attributed to the formation of lateral gas envelopes. In particular, test tuyeres in the tuyere line tended to operate synchronously at the dominant frequency, regardless of operating conditions tested and despite being distributed along the converter. Synchronous behavior is thought to arise from the acoustic coupling and possible resonance behavior of the gas delivery system on the converter.

Jan 1, 2007

By A. Robles-Vega

Personnel of Mexicana de Cobre, a subsidiary of Southern Copper located in Nacozari, Sonora Mexico have been working in the past few years on the development of a process to treat and manage, in an environmentally accepted practice, the residues and effluents generated during the process. To date, this team has been reviewing existing technologies and also has explored new alternatives. At the end of this phase, a novel, efficient and complete process has been configured which will be able to treat some solid and liquid streams such as Teniente converter dust, Peirce Smith converter dust, a Sb-rich precious metals slag, copper refinery electrolyte bleed, acid plant blowdown and an acid bleed of the precious metals plant. The process will consist of a leaching stage, followed by a very selective copper precipitation using novel technology which has been named as back reactions. After copper precipitation, impurities (As, Sb and Bi) will be precipitated mainly as arsenic trisulfide (As2S3) using H2S(g) which will be generated by means of a new process developed in our company. At the end of the process, small volumes of arsenic trisulfide will be vitrified and then disposed as a stable residue.

Jan 1, 2007

This paper investigates the effects of solids concentration and the addition of Dispersant S40 on the flowability of original and ground limestone slurries. A rotational viscometer with a concentric cylinder geometry and a controlled-stress rheometer with a cone-and-plate geometry were used to characterize the rheological behaviors of limestone slurries. The rheological behavior of original limestone slurries (<100 µm) is transformed through different types of flows with increasing solids concentration. The use of Dispersant S40 can improve the slurry flowability by decreasing viscosity and eliminating Casson yield stress. It is therefore used as a grinding aid for the wet ultrafine grinding of limestone. The rheological behaviors of ground limestone slurries vary with grinding from a starting dilatant flow-ability to a resulting pseudoplastic one with an evident Casson yield stress in combination with a thixotropic character. The appearance of pseudoplastic flowability combining thixotropy is related to the fineness of a ground product and its specific surface area, which are both correlated to solids concentration and the additive amount of Dispersant S40. In addition, the accurate rheological characterization of time-dependent fluids is dependent on the instruments used and operation conditions.

Jan 1, 2007

By P. E. Walker, M. E. Reed, R. C. Sims, B. Snowdon, D. E. Fallas

An advanced Flash Furnace feed system is the key to improving furnace performance. Clyde-WorleyParsons has developed a revolutionary pulseless pneumatic injection feed system technology, capable of delivering a range of benefits to operators of Flash Furnaces. The solution was created by combining the pneumatic conveying and injection knowledge, expertise and technology of Clyde Materials Handling with WorleyParsons&apos; flash furnace process and operating experience. Optimal furnace burner performance requires the feed material to be presented to the burner as a stable, pulseless and accurately controlled flow, distributed evenly around the burner tip circumference. These simple requirements appear obvious, but are extremely difficult to satisfy in industrial environments and are not achieved by conventional feed systems. Our analysis of existing operating furnaces has identified the link between pulses in concentrate feed rate caused by conventional drag chain conveyors and rapid fluctuations measured in the furnace pressure. These fluctuations occur at a timescale close to the reaction shaft residence time and lead to unwanted instability in the primary furnace reaction zone - the flame. Through the use of the solution created by Clyde-WorleyParsons, it is predicted that the much more accurate control of feed rates achieved can lead to substantial improvements in furnace output, increased oxygen efficiency and better control of the composition of furnace liquids, such as matte, blister or slag. All these improvements lead to significant increases in smelter output and efficiency, and deliver high economic value compared to the cost of the feed system. Clyde-WorleyParsons&apos; solutions can be deployed on greenfield sites or retrofitted, and therefore, have the capability to improve feed control at both new and existing smelters. This paper will discuss the field test work undertaken to date, the impact of findings and the ongoing analysis of linkages between instabilities in the various components of conventional feed systems and furnace pressure stability.

Jan 1, 2007

Existing production facilities are constantly looking at ways to increase capacity. Many recent solutions have focused on the implementation of capital and infrastructure projects. It is accepted that capital expansions are frequently necessary for production gains; however, in many cases existing assets have the potential to deliver substantially better throughput than they are currently achieving. By focusing on automation of production control systems, production reporting and business processes substantial gains can be achieved utilising existing assets. This potential can be realised quickly and has been proven across several sites and industries. In the Pilbara region of Western Australia throughput gains of between two per cent and 25 per cent (translating to millions of tonnes per annum) have been achieved from existing assets using the methodologies discussed. The improvement process involves evaluating the entire production chain from the time the ore arrives at the plant to the time it is dispatched. A technical evaluation of the performance of the control system and plant automation interfaces to upstream and downstream processes is conducted. The relationship of these processes to the business systems and the human interface to the systems is reviewed to ensure a complete picture of the system is understood. Technical evaluation targets include: individual equipment operation, the engineering level of control systems, feed controls, etc; managing recirculating loads, surge capacities, dynamic inventories as well as management of in-feed systems and integration into yard and out-feed systems; and communication flow between control and other systems, data alignment between rail and shipping schedules, yard systems, sales systems and maintenance systems including such fundamentals as truck dispatch links to plant control. In parallel with the technical evaluation, business system evaluation takes place, including analysis of the operational systems, methods and personnel.

Jan 1, 2007

By M. H. Ali

Codelco, a multi-process primary copper producer, is undertaking a full life cycle inventory (LCI) of all its commercial products based on copper and molybdenum. During this work, many questions have surfaced regarding the contribution of process unit design to specific aspects of a product&apos;s LCI and, more importantly, how such designs could be improved using a life cycle perspective. Management strategy efforts were undertaken to improve the LCI footprint, however it was found that the corrective actions were almost impossible to apply at the operation level in plant, given the ongoing timing pressures of extractive mining, and costs saving priorities. Additionally, it was found that most of the important comparative differences between operations had structural reasons. In this circumstance, the LCI practitioner group from 1M2, and the environmental managers from Codelco, decided to shift its efforts to place the critical LC1 aspects to the design process of future developments. Hatch Associates has developed unique tools in their Sustainable Plant Design (SPD) package that compliment and enhance LCA methods; these effectively drive sustainability into the heart of the design process. By using LCA and SPD in a project design phase, you cannot only address potential hotspots, but also decide on materials, location and size of certain facilities to optimize for energy efficiency. Moreover, you can avoid the shifting of environmental burdens upstream or downstream within the plant and finally it is extremely useful in identifying opportunities for greenhouse gas reduction.

Jan 1, 2007