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By W. A. Toohey

Introduction From the earliest times it has been an inherent trait of man to build or create something for his own use or convenience. The need of some form of shelter other than that of the caves led him to bind together stones and other materials to form walls for his abode. Moistened clay which hardened upon drying was no doubt first employed. The Assyrians and Babylonians appear to have employed it or the bitumen found in their country. The early Egyptians and Greeks used some form of lime in their construction work. In addition to these shelters, other structures received attention, and, long before the Roman Empire was established, the Carthaginians made use of a natural cement as binding material. Portions of an aqueduct, seventy miles long, in Northern Africa, built in those early days, are still in use. The Etruscans were the first people in Italy to employ a mortar in their buildings. The Romans, learning the art from the Etruscans, improved the mortar by using a mixture of lime and volcanic ash, called 'puzzolan', and built not only roads but those famous structures, the ruins of many of which exist to this day. The Pantheon at Rome, built by Hadrian about 120 A.D., is perhaps the finest example of the early use of cement in building construction. With the decline of the Roman Empire, the art of making cement seems to have been lost, and for centuries the builders of Europe used only lime mortar. Pure limestones were selected for making the lime and great care was taken in the preparation of the mortar, the supply for one year being made the previous season and left to thoroughly slake or 'ripen' in pits covered with earth. The mortar thus produced gave excellent service above ground or where it was exposed to the hardening action of the air, but would not harden under water.

Jan 1, 1927

By D. Markwart, B. Volk

Anode effects are a phenomenon of the aluminium electrolysis process which produce potent greenhouse gases called PFCs (CF4, C2F6). With concerns surrounding global warming, and increasing regulation of GHG emissions, anode effects have become a significant sustainability issue for aluminium producers. In modem smelters, sophisticated computer control and automated alumina feeding systems allow for very tight control of the alumina concentration in the electrolyte and thus very low anode effect frequencies. Older smelters, however, do not have these systems and must either invest heavily to obtain them, or find other, innovative ways to reduce anode effect frequency. This paper will present the integrated approach to anode effect reduction used in the Vertical Stud Soderberg (VSS) potlines at Kitimat Works. Through an innovative combination of simplified signal analysis, modified alumina feed control logic, anode effect prediction, and anode effect prevention using a pager based communication system, Kitimat W arks has been able to make significant reductions to its anode effect frequency.

Jan 1, 2006

By Wei Yingchun

Based on the deep burial depth of coal deposits in Huainan-Huaibei coalfields, Anhui Province, China, this paper puts forward the concept of partitioning of coal deposits according to occurrence conditions. This process is controlled by tectonic forces. The classification scheme of coal deposits exploration types is presented according to occurrence and mining conditions of coal deposits as viewed from the perspective of deep coal exploration properties. The principles underlying geological exploration services for the resources development are incorporated. There are six exploration types of coal deposits in the Huainan and Huaibei coalfields. Exploration models tailored to different types of exploration have been established and exploration strategies corresponding to different exploration models have been proposed. Steady-state temperature must be measured for the deep heat-harm type of coal deposit. The sealing coring of mine gas samples should be performed for the high mine gas type of coal deposit. For coal deposits with complex structures, such as those located beneath nappes, coal-controlling structural styles must be performed. Existing data on shallow districts are very important to the research of folds and fault-block types of coal deposits beneath and peripheral to old and existing coal mine areas. For the types of fault-block coal deposits hidden by thick Cenozoic cover, particular attention must be paid to comprehensive use of research on regional coal occurrence law and geophysical methods. The present work promotes the exploration level of coal deposits in Huainan-Huaibei coalfields to best meet the need for sustainable development of the coal industry.

Aug 1, 2013

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimizing the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give account of the uranium processing optimization journey embarked on over the years; namely, the operational trade-offs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper.

Jan 1, 2020

By Guocheng Pan

"Although many factors play roles in the estimation of recoverable reserves, smoothing effect and conditional bias are considered major geostatistical issues in the estimation. This paper introduces measures for smoothing effect and conditional bias, and provides insights into their relation to the estimation of recoverable reserves. Both smoothing effect and conditional bias are intrinsic to the information effect and kriging estimators. For a given level of drilling information, however, it is possible to identify the optimal search radius that minimizes conditional bias. Furthermore, it is also feasible to define variance correction factor for reduction of the smoothing effect from exploration block models. Both of these components are key to the accurate estimation of recoverable reserves. IntroductionThe accurate estimation of recoverable reserves is critical to decision making in different phases of feasibility study and mine planning. Much attention for improving the methodology of estimation has been focussed on the effect of the change-of-support (Parker, 1980; Dagdelen, 1996). For example, it is essential to make a volume- variance correction to the estimate of multiple indicator kriging (Hoerger, 1992). When the size of block, b, in the geostatistical model differs from that of selective mining unit (SMU), v, a volume-variance correction is warranted for the prediction of recoverable reserves.Most mining plans and decisions are made prior to the availability of high density blast-hole samples. In most mining operations, the true SMU grade Zv is unknown at the time of selection. Instead, the selection is based on the estimate Z v**derived from high density blast-hole samples within the deposit G. Nevertheless, the estimate Z v * of recoverable reserves in the stage of mine planning is derived from exploration data. At the end, the production result must be reconciled to the estimate Z v * . In other words, the selection is based on Z v** from blast-hole samples, while the final production figures are reconciled to Z v * from exploration drilling. For a given preselected cutoff grade z0, the actual mining panels will consist of the units having the estimated grade Z v** =z0 rather than the true grade Zv =z0. The difference between Z v** and Zv is usually of less concern."

Jan 1, 1998

By R. Ramirez

Atlantic Copper Refinery (Huelva, Spain) has operated the ISA permanent cathode technology since 1995. The current production rates are 260,000 t/y cathodes and 730 t/y anode slimes. These slimes undergo an atmospheric leaching in which their copper content is reduced from an average value of 24 % to 16 %. In June 2005 an optimization study of the leaching conditions was carried out aimed at lowering the copper content in the slimes to less than 8%. At the same time, a new mixer (Outukumpu Technology GLS-mixer) was installed in one of the three leaching reactors. As a result of the improvement of the leaching performance and to prevent the return of tellurium to the tankhouse, a cementation plant was commissioned in July 2005 to ensure a Te content below 50 ppm in the Cu-rich leachate. This paper describes the results of the improvement of the leaching conditions and the operation of the new tellurium removal plant.

Jan 1, 2007

By Laxman M. Amaratunga

"The fine fraction of tailings is usually excluded from the backfill process and generally disposed on the surface in tailings ponds. Because of the ever increasing demand for fine grinding in the extraction process for improved liberation of valuables in the ore, increased production of fines in the tailings has resulted. The negative impact of surface impoundment of tailings on the environment is well known. Amaratunga and Annor (1989) first presented a concept of fine tailings agglomeration for backfill.This paper presents the development of the novel cold-bond tailings agglomeration (CBTA) technology for non-reactive fine gold mill tailings. For cold-bond agglomeration regular portland cement was used as a binder. In order to cut costs, alternate binders such as lime, and blast furnace slag cement were examined. The effects of binder dosage, curing time, and agglomerate size on the fracture load strength of the agglomerate were studied.Fine tailings agglomerates are mixed with coarse tailings or non-agglomerated fine tailings to make high density fill compositions to be used as underground backfill. Alternatively, the agglomerates can be used as aggregates for surface applications. The paper discusses the environmental and operational benefits of this total tailings utilization and disposal technology.IntroductionIn Canadian mines, mill tailings are probably the most commonly used material for backfill. However, only the coarse fraction of tailings is desirable for use as hydraulic fill or high density fills. The fines are disposed on the surface in tailings ponds since they are unsuitable for underground backfilling owing to the following factors:i) slow settling ratesii) longer percolation timeiii) excessive consumption of binder due to drainageiv) poor compactionFor improved value liberation more milling operations have resolved to fine grinding in their comminution circuits. Gold milling operations driven by down stream leaching processes grind their ores excessively fine. In general, gold mines use hardly any tailings for backfilling. This can result in periodic short falls and the need to search for alternate backfill material from other sources. Apparently, the gold producers are the most identifiable sector which suffer from a shortage of backfill materials ( Amaratunga and Annor, 1989)."

Jan 1, 1994

By C. A. Campbell

"There has been a significant reduction in maintenance hours and improved performance by maintenance crews at the MacLeod mine since the introduction of a Maintenance Control system which includes the use of maintenance standards. This paper deals with the steps taken to develop and implement the program. The objectives of the program and the organization and training of the control group are outlined. The work-order system, standards application, classification of work and the preventive maintenance procedures will be discussed.All maintenance information is processed on a Model 360-20 IBM computer, which turns out maintenance records and control reports for management action. Information in these reports, and reasons for reporting, will be discussed and the benefits resulting from the program reviewed."

Jan 1, 1973

Over five decades ago Kitchener et al. in England and La Mer and Healy in the US were advancing our understanding and application of flocculants, primarily related to water treatment and filtration of sludge. This paper identifies the beneficial uses of flocculants in the mining industry and revisits some less common applications. Flocculants are used in unique ways in the mining industry: (a) to increase the effectiveness of sediment ponds to achieve discharge compliance; (b) to eliminate air emissions and costs associated with concentrate drying; (c) to reduce soil loss by applying a flocculant to erodible soils, and reducing wind and water erosion; (d) to remove/thicken metal precipitates in acid rock drainage treatment; and (e) to enhance clarification and thickening in mineral processing. The mechanism of how flocculants, coagulations and potentially-determining ions function is described and how their use can be controlled and optimized. The potential toxic effects of flocculants and coagulants when used to achieve effluent permit discharge compliance for suspended solids is discussed. A review of numerous best management practice (BMP) guidelines for the design and operation of sediment ponds treating mine site runoff to remove total suspended solids (TSS) and turbidity revealed an absence of a predictive methodology to address regulatory discharge compliance for TSS concentration, turbidity and flocculant-induced toxicity. An essential component of pond design is the need to determine whether flocculants and/or other settling aids are required based on the site-specific soil particle size distributions upslope of the pond. Procedures are provided to predict the need for settling aids and estimate pond discharge quality and downstream impact for TSS, turbidity, toxicity and sub-lethal toxicity. The need to develop BMP guidelines are discussed for (a) the application of flocculant to surface soils to reduce erosion, (b) the application of flocblocks to increase the ?sediment control? aspects of erosion and sediment control, as part of the mine site erosion control plan strategy and (c) the application of flocculant to silt socks to treat mine site runoff.

Aug 1, 2013

By William E. Roscoe

"Valuation methods are well established for mineral properties with production or imminent production, and include discounted cash flow and comparable transactions. Valuation methods for non-producing mineral properties, however, are more subjective. Non-producing mineral properties include those at various stages of exploration, properties at the prefeasibility or feasibility stage, properties with currently uneconomic mineral resources, and past-producers. Different valuation methods may be appropriate for different types of mineral properties.Income approach methods such as discounted cash flow and option pricing are generally not applicable to properties at the exploration stage. The market approach is generally appropriate to all types of mineral properties, although it is difficult to find good comparables because of the unique nature of mineral properties and the small number of transactions. Cost approach methods, such as appraised value and geoscience factor, are commonly used for exploration stage properties.Canadian standards and guidelines for valuation of mineral properties are in the process of being finalized by a Special Committee of the Canadian Institute of Mining, Metallurgy and Petroleum (CIMVal Committee). The CIMVal Standards are intended to be consistent with National Instrument 43-101, which sets regulatory standards of disclosure for mineral projects, and with International Valuation Standards. The intent of the CIMVal Standards and Guidelines is that mineral property valuation be carried out by appropriately qualified individuals and that all relevant information be disclosed."

Jan 1, 2003

By 000-900-009-492

The flotation has been and is still the most widely used mineral concentration method. Because of its complexity, the flotation process required the development of robust control strategies which was facilitated by the introduction of on-line sensing instruments such as x-ray fluorescence (XRF) on stream analyzer (OSA), gamma density gauges and electromagnetic flowmeters. The interest in developing control strategies has persisted because the benefits to be gained in terms of improved metallurgical performance are substantial. As the flotation control becomes more and more difficult due to the emergence of low grade and complex ore cases, other control strategies have to be introduced. Froth based control is one of the emerging useful control strategy This paper will focus on the state of the art in the on-line froth characterization as obtained by numerical image analysis. The technology of machine vision provides a novel solution to several of the problems encountered in conventional flotation systems for monitoring and control, and constitutes a powerful tool for the investigation and interpretation of the effect of various flotation parameters as driven for the froth phases. Copyright @2001CIM

May 1, 2001

By D. W. Hendriks, C. Daoust, K. V. Konigsmann

"The concentrator of Mattagami Lake Mines Limited commenced operation in 1963. It had been designed with instrumentation proven at that time. New control techniques were added in subsequent years.An on-stream X-ray analyser was installed in 1968. It provided circuit analyses for six years without the aid of a computer. In late 1974, control of the flotation circuit by computer was incorporated into the system. Flotation efficiency improved considerably, zinc"" recovery increased by one percentage point and concentrate grade by four-tenths of a percentage point. Reagent costs decreased modestly through reduction of copper sulphate consumption."

Jan 1, 1976

By Da-Qiang Cang, Qingde Wang, Wei Wang, Wen-Bin Dai, Min Guo, Yu Li

Utilization of both slag and its heat for hot slag is a great challenge for iron and steel industry. Many methods of hot slag modification for directly converting hot slag into value-added materials were researched in recent years, and waste heat of hot slag could thereby be transformed into inner energy or chemical energy of the materials. In this paper, an experiment of converting hot slag directly into glass ceramics by hot slag modification method was conducted. A cooled modifiers mainly composed of fly ash were firstly heated though a cyclone furnace and then fell into a molten bath to mix with hot steel slag. Half of hot slag was used as raw materials and accordingly about half energy consumption, about 5MJ/kg for melting raw materials was saved in the process compared with that of traditional producing method. Frit quenched from the modified hot slag had a higher basicity of 0.6-0.7 than traditional frits in order to reduce the needed amount of cold modifiers and accordingly utilize more hot slag and its waste heat. Glass ceramics were further prepared from the frit and a heat treatment of one-stage method is more suiter to such frit than that of two-stage method. The glass-ceramics with basicity of 0.6 and heat-treated by one stage method had the best performance with bending strength of 146.46 MPa, Vickers hardness of 6.79 GPa, water absorption rate of below 2% and shrinkage rate of around 10%.

Jan 1, 2015

By R. E. Hamilton

"The requirements for effective optimization of a mineral dressing operation are discussed, with specific reference to a flotation system . Also considered are the relation-ships between automatic control and optimization pro-grams. Variables are classified into the following groups, and the significance of the classification is discussed: (a) Directly measurable (b) Directly manipulable (c) Uncontrollable (d) Calculable from measurable variables (e) Affected by changes in manipulable or uncontrol-lable variables. New sensors for measuring variables not normally measured are described."

Jan 1, 1967

By D. J. Farmer

Mining hoists are major components of any underground mine, however, the detailed design work required to get the actual power required for a particular hoist is outside the scope of preliminary feasibility studies. Nonetheless, a hoist is costly. Therefore, an accurate estimate is needed for the design parameters and the power required. There are two methods available, namely, the O’Hara method and the Society of Mining Engineers’ method. Tests were done for both methods employing nine friction hoists and 19 drum hoists currently in use at Canadian mines. The O’Hara method provided unacceptable results for both friction and drum hoists. While, the SME method was designed for American regulations and factors of safety which often differ significantly from Canadian ones, good results were obtained. The two relationships deter-mined were simply to add 5% to friction hoist design and to add 4% to drum hoist design. Modifying the SME method by these two factors will allow the hoisting system determined by the SME method to be within the error for a prefeasibility study.

Jan 1, 1997

By P. Leo

Al-Mg-Si alloys are widely used as medium-strength structural materials; extrusion is the most common processing route. In the present hot deformation investigation of a 6060 alloy, the microstructure of the alloy has been analyzed in the as-cast state, after homogenization heat treatment and after hot deformation by tensile tests in the range 400-490°C and 10-4 to 10-2s-1 on both as cast and homogenized alloys. After deformation the microstructure of the as-cast alloy exhibited cavitation. The flow curves at the lowest test temperature T show a gradual softening after a stress peak, being more evident for the alloy deformed in the homogenized state in association with a high yield stress; at higher T a plateau is attained which is lower as T rises and strain rates decrease. For each fixed T, the ductility decreases as strain rate increases for the homogenized alloy whereas, for the as cast alloy, it rises with strain rate. Constitutive analysis gives Q = 240kJ1mol for the homogenized alloy in agreement with published values; this indicates a more rapid strength decline with rising T than Al, suitable for good hot workability along with the lack of cavitation.

Jan 1, 2011

By J. G. Cullain

Inco Limited is an integrated mining, smelting, refining and manufacturing company with operations located worldwide. The Ontario Division operations consist of 13 mines and 10 processing facilities located in Sudbury, Port Colborne and Shebandowan. The scope of our utilization of energy in the Ontario Division in 1976 included in excess of 2.2 billion kilowatt hours of electric power, 12 billion cubic feet of natural gas, 60 million Imperial gallons of residual oil and smaller quantities of other fuels. In addition to the primary energy consumption, waste-heat energy is recovered in various operations throughout the Division, thereby reducing our primary energy requirements. Total expenditures for primary energy alone in 1976 exceeded 60 million dollars. Energy management studies were initiated by Inco's Utilities Department in late 1972, and resulted initially in a program of electric power cost reduction. This program produced significant results by improving the use of the water available for our hydraulic generation facilities and by a comprehensive peak reduction program. Our experience showed that a program of peak power control creates an awareness of both peak and energy costs, and thereby encourages a general reduction in the electric energy consumption as well as lowering the peak demand. Energy management is a continuing program at Inco and, recently, a formal energy management policy and program was instituted. Energy management committees were formed in each plant or mine area to identify the major areas for energy; consumption, thereby isolating areas with large potential energy losses, and determining immediate action which will improve the energy efficiency or reduce the energy waste within their respective areas. A decentralized program with good cross-communication between all committees was felt to be the best method of providing an on-going effective energy management program. In the future, the projections of dwindling fossil-fuel supplies in Canada and the resultant spiralling energy costs will further emphasize the need of sound energy management practices for all Canadian industry.

Jan 1, 1977

By C. G. McLachlan

Abstract This paper deals with the application of the cyanide process to recover gold from a pyrite concentrate produced by means of differential flotation. This concentrate before cyanidation contains from 0.09 oz. to 0.14 oz. gold per ton, of which only about 60 per cent is recoverable. The rest is so fine that it remains interlocked in the pyrite and therefore is not acted on by the cyanide. The concentrate also contains about 15 per cent pyrrhotite and 0.4 per cent chalcopyrite, both of which are cyanicides. The cyanicidal effect of the pyrrhotite is inhibited by preacracing the pulp with lime, and maintaining a high lime alkalinity during cyanidation. The effect of the chalcopyrice is reduced as far as possible by removing those particles which are free by means of a further flotation step immediately prior to cyanidation. This involves the flotation of some very fine material. After nullifying as far as possible these two cyanicides, the concentrate is cyanided directly, i.e., without being roasted. This leaves the pyrite available for subsequent sale as a source of sulphur dioxide and sulphuric acid, and the entire residue of the cyamde plant, amounting to about 500 tons per day, 1s now being disposed of in this way. Prior to deciding on direct cyanidation, a number of laboratory roasting tests were made. These showed chat, 1f proper control were exercised, a better recovery of gold could be effected from the roasted product than by the direct method of treatment. The tests also showed that the capital cost o the plant would be much higher than that needed for the procedure adopted. The possibility of subsequently selling the pyrite for its sulphur content would also have been eliminated. Introduction A previous paper has described in considerable detail the application of the flotation process to improve gold recovery from Noranda's milling ore, and in so doing has covered the production of an auriferous pyrite concentrate. The present paper deals with the recovery of gold by cyanidation from that concentrate. This gold, though intimately associated with the pyrite, can, for metallurgical purposes, be considered as all occuring in the native state.

Jan 1, 1946

By Timothy W. Ellis, Abbas H. Mirza, R. David Prengaman

Recycled lead, i.e. material produced by the recycling of lead-acid batteries, has become the primary source of lead in much of the world. This has been important to the recycled lead industry as other uses have dwindled, e.g. lead based pigments, chemicals, fuel additives, solders and CRT glasses. Presently, battery manufacturing accounts for greater than 85% of lead consumption worldwide while recycled lead accounts for approximately the same market share of lead supply. Battery manufacturing and production of recycled lead are intimately coupled. In 2007, of all the industrial base metals, lead from lead-acid batteries had the highest recycling rate in North America at greater than 95%. In this paper we will review some of the processes and technologies used in a modern lead acid battery recycling facility, and how recycled lead has become the material of choice for battery construction through the development of a recovery and refining process that exceeds the industry requirements. We will also briefly review an advanced air emissions treatment system in a modern lead recycling plant that demonstrates the feasibility of a new maximum available control technology (MACT) for secondary lead smelters.

Jan 1, 2011

By D. H. Schwarz

The performance of proton exchange membrane (PEM) fuel cells depends on catalyst layer composition and structure. Experimental observations reveal that state-of-the-art catalyst layers consist of microporous agglomerates of carbon-supported catalyst sites bound together by polymer electrolyte. In between the agglomerates are macropores which provide pathways for the transport of gaseous reactants. In this work, three-dimensional, multicomponent and multiphase transport computations are performed using a computational fluid dynamics (CFD) code (FLUENTTM) with a new PEM fuel cell module, which has been further improved by taking into account the detailed composition and structure of the catalyst layers using a multiple thin-film agglomerate model. In this model, it is assumed that thin films of polymer electrolyte and liquid water surround the catalyst sites. The results of CFD computations show that transport limitations associated with the thin film of polymer electrolyte and the presence of liquid water in the catalyst and gas diffusion layers have substantial negative effects on PEM fuel cell performance. Also, the results of computations with variable distributions for a given precious metal loading show that, in general, uniform catalyst loading provides the best fuel cell performance.

Jan 1, 2005