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By C. J. Newman, K. Molnar, A. G. Storey, G. Macfarlane

"The Kidd Creek copper smelter started operation in June 1981 using the Mitsubishi Continuous Smelting Process. A steady increase in plant production rates has been demonstrated, and the annual tonnage of concentrate smelted is now double the original design rate. This paper summarizes recent modifications made to increase concentrate feed rates, increase on-line time, reduce copper losses and control the impurity level in anode copper. It includes improvements made to furnace design, improvements to reduce downtime f or boiler cleaning, and improvements made to the acid plant to allow handling of increased gas flowrates and higher gas strengths while maintaining low acid plant emission rates. IntroductionThe Kidd Creek Division of Fal conbridge Limited operates a base-metal mining and metallurgical complex, located in Timmins, Ontario, which includes an underground mine, a 13 500 tonne/day concentrator, a 130000 tonne/year zinc plant and a copper smelter and refinery, The copper smelter and refinery were commissioned in 1981, with an installed capacity of 59 000 tonnes/ year of cathode. The smelter, utilizing the continuous smelting technology of the Mitsubishi Process, has subsequently been expanded in production capacity, and in 1991 produced 113 500 tonnes of blister copper The capacity of the refinery, which uses Onahama No. 3 tankhouse technology, has been increased to 96 000 tonnes/year of cathode. The capacity increase at the smelter has been realized through the input of additional oxygen to both the smelting and converting furnaces, without increasing the process off-gas flowrate through the associated waste heat boilers.In this paper, a brief review of smelter operation and modifications in the period 1982 to 1987 is presented, together with a more detailed discussion of operation during 1988 to 1991, and a discussion of future planned improvements."

Jan 1, 1992

By Fathi Habashi, Michel Pagé, Farouk T. Awadalla

"Chrysotile asbestos can be dyed with certain dyestuffs to form stable coloured products whose hemolytic and cytotoxicity are greatly reduced. Examples of these dyes are Thiazol Yellow G (a monazo dye) and Trypan Blue (a diazo dye). Other dye stuffs, for example, basic dyes with triphenyl methane structure, Brilliant Yellow (a diazo dye), and Methylene Blue (a thiazine dye) colour asbestos but do not reduce its toxicity. Similarly alizarin, 8-hydroxyquinoline, and representative members of the phthalein group Bromocresol Purple and Phenolphthalein.IntroductionThere is, at present, a controversy regarding the dangers of asbestos fibres, and attempts are being made to render it less toxic. One of these attempts consisted of treating chrysotile asbestos with gaseous phosphorus oxychloride, POCI], at ambient temperature and in absence of moisture. The product had to be heated at 300°C to 500°C to expel exess entrained reagent to get a material containing 0.5070 to 5% phosphate groups and known as Chrysophosphate (Lalancette and Dunnigan, 1982). This product showed decreased toxicity as measured by its hemolytic effect on red blood cells (fable 1). In another approach, Flowers (1983) showed that when chrysotile asbestos was thoroughly mixed with a solution of ferric ammonium sulphate and the slurry was then filtered and dried, the product showed a marked decrease in cytotoxicity.In the present investigation the problem of toxicity was considered from a different point-of-view. Chrysotile asbestos is a hydrated magnesium silicate that can be represented by the structural model shown in Figure 1 from which it can be seen that magnesium hydroxide groups, Mg(OH)2, form a part of the silicate structure. Certain organic reagents that are known to react with magnesium ion in solution to form chelates were reacted with asbestos to find out whether a chelate was also formed on the fibres, and if so , what will be the hemolytic action and cytotoxicity of the product."

Jan 1, 1991

By J. E. Dutrizac, Alba Sunyer

The factors affecting the precipitation of arsenic-free alunite (KAl3(SO4)2(OH)6) were investigated in a series of laboratory experiments. Although the amount of alunite precipitated increased with increasing retention time, temperature, solution pH and the concentrations of Al(SO4)1.5 or K2SO4, the composition of the products remained nearly constant. The preferred conditions identified for the precipitation of arsenic-free alunite were then used to assess the behaviour As(III) and As(V) during alunite precipitation at 98°C. Increasing additions of As(III), as NaAsO2 or As2O3, resulted in a slight increase in the amount of precipitate formed at pH 2.80. However, X-ray diffraction analysis showed all the precipitates to be alunite, and <0.2% As(III) was detected in the products. In contrast, increasing additions of As(V), as KH2AsO4 or As2O5, resulted in significant increases in the amount of precipitate formed at pH 2.80 or 3.00. Furthermore, the arsenate (AsO43-) contents of the precipitates increased up to 15%, and the sulphate contents decreased, as the As(V) concentration of the synthesis solution increased from 0 to 9 g/L. X-ray diffraction analysis of the products detected only alunite, but there was a progressive expansion of the alunite cell with increasing arsenate content. The implication is that arsenate substitutes for sulphate in the alunite structure. Preliminary observations on the environmental stability of the arsenate-bearing alunite using the TCLP protocol gave solubilities <0.4 mg/L from a precipitate containing 8.5% AsO4 and 7.8 mg/L from a product containing 19.5% AsO4. Thus, it appears that alunites containing less than -10% AsO4 would be an acceptable vehicle for the disposal of arsenic from hydrometallurgical processing solutions.

Jan 1, 2011

By Y. Huang

Corrosion of GaAs in aqueous electrolytes is a major limitation in implementing GaAs-based photoelectrochemical solar energy conversion systems, In this work, the corrosion behavior was investigated by electrochemical methods and surface analysis approaches, in both H2SO4 and NH3?H2O solutions, Open-circuit measurements showed that the cleaned GaAs surface was very sensitive to water/air, Impedance measurements for n-GaAs showed that an inductive loop only appeared at a high corrosion rate because a reaction intermediate is the oxidant for a further decomposition step in combination with chemical reaction with water, The results suggest that the same corrosion/decomposition mechanism occurred on n-GaAs in the two solutions, When the surface-hole concentration was low, the hole injection or generation process was the rate-determining step, At large reverse bias on n-GaAs, with high-hole concentration, the corrosion rate was limited by a Faradaic adsorption process, involving an adsorbed intermediate, The different surface compositions after corrosion in the two solutions can be explained by the dissolution of As(0), Further oxidation of As(0) to As(III) in NH3?H2O solution is still slow, as suggested from X-ray photoelectron spectroscopy (XPS) analysis,

Jan 1, 2005

By D. J. Reddish

The paper describes a case study where numerical modelling has been applied to predict potential risks associated with inflows of water in active mine workings from an overlying sandstone aquifer. The objective of the modelling was to predict the development of strata fractures and strains as the longwall panels were extracted and investigate their relationship to an sandstone aquifer. The numerical modelling study also included the investigation of the effect of mining on a fault that existed close to the start position of one of the panels. The potential effects of mining on the fault were undertaken by parametric studies adjusting properties for the fault and the relative position of extractions, which allowed the mine planner to position the panel layout accordingly.

May 1, 2003

By G. S. Hume

Research thrives on ideas, and the theoretical considerations of today are either the discarded notions or the proven facts of tomorrow. The progress made in the past fifty years in the acquisition of knowledge of petroleum geology is no less astounding than is the tremendous increase in the production of oil on the North American continent from 61 million barrels in 1897 to 1,917 million barrels in 1947, an increase of 3,300 per cent, with production of natural gas expanding from less than 400,000 Mcf in 1897 to approximately 4,500,000,000 Mcf, or an increase of 11,000 fold in the same period. In the search for and discovery of the oil and gas fields that have yielded such prolific wealth, no idea has had a more profound effect than has the ?anticlinal? theory of oil accumulation, propounded in 1844 by Sir William Logan, the founder of the Geological Survey of Canada, after noting the position of oil seepages on the crests of anticlines in Gaspe peninsula. Sir William apparently was not much impressed with his own idea at this time, but after the Drake well discovery in 1859 and the publication by Henry D. Rogers, of Glasgow University, formerly of the Pennsylvania Geological Survey, of a paper in which he pointed out that the seepages in Pennsylvania were on anticlines, T. Sterry Hunt, an associate of Sir William Logan on the Geological Survey of Canada, published a reasonably comprehensive statement of the anticlina theory in the Montreal Gazette on March 1st, 1861. Hunt recognized the fact that the oil ?being lighter than the water which everywhere penetrates the rocks below the water level, naturally rises and accumulates along the crown of these anticlines". This was a recognition of the fact that gas, oil, and water in an anticlinal structure separate according to buoyancy or specific gravity. For some years the anticlinal theory does not seem to have attracted much attention, but when I. C. White in 1883 revived it and put it to practical use by prospecting for &apos;anticlinal&apos; oil an gas structures in Pennsylvania, West Virginia, and Kentucky, its real value not as a theory but as a fact became widely recognized. Even today, the search for anticlines as oil and gas structures is being vigorously continued. In the past fifty years, however, it has become widely recognized that petroleum and natural gas collect in many different types of structures, and these have become known by the general name of &apos;traps&apos;. About 1890, terrace structures were highly regarded because it was thought certain oil fields in Pennsylvania, New York, and Ohio were directly related to them. However, as Wilson (2, p. 437) has pointed out, it is recognized to day that ?&apos;wherever the surface evidence is complete and dependable, other factors (than the terrace structure) are found to be in control&apos;.

Jan 1, 1948

By Ray Collier

MINING TODAY l EXTENSIVE AND EXPENSIVE PERMITTING PROCESSES WITH UNKNOWN RESULTS l GENERAL AND IMPASSIONED RESISTANCE TO RESOURCE BASED INDUSTRY l SOPHISTICATED, ORGANISED, AND WELL FUNDED OPPOSITION l MOST LOCAL GOVERNMENT DOESN?T WANT MINING TODAY?S TALK l FOUR SPECIFIC OPERATIONS ON WHICH OUR EXPERIENCE IS BASED ? SECHELT ? CADMAN ? GRANVILLE ISLAND ? LEHIGH CEMENT DELTA PLANT l OUR APPROACH TO COMMUNITY RELATIONS

May 1, 2002

By J. Peace, J. R. Fletcher

"British Steel has increased its usage of stainless steel for bunker, silo and chute linings to reduce maintenance costs and improve productivity.A generation of low cost 12% Cr steels has been specifically developed to satisfy the needs of hardness, flow promotion and through life costing which are demanded by bulk solids handling industries.The range of stainless steels include:• a very hard martensitic grade which is particularly suitable for high stress applications where impact and abrasion are predominant;• a titanium stabilized duplex steel for structural applications, as well as low friction , medium abrasion resistant wear liner plate; and• a ferritic stainless steel with rubber backing for low stress application where flow promotion of product is the predominant requirement.Industrial applications and experiences along with methods of fixin g the stainless steels will be discussed in conjunction with the relative through-life costs of the products.IntroductionBritish Steel has become one of the most efficient steel manufacturers in the world, with improvements seen in productivity, quality, delivery, performance and response to the needs of the worldwide market place.Part of this success stems from reductions in engineering downtime in the key areas of its operations, by the introduction of better engineering design and the use of enhanced materials where significant cost benefits have been identified.The nature of producing iron and steel requires the use and handling of a number of raw materials with wide ranging properties, each calling for a different approach to solving the difficulties encountered in storing and transporting these materials to their respective point of use. Figure 1 shows steel production for 1988-89 where over 30 million tonnes of raw materials were handled in making 14 million tonnes of liquid steel at British Steel&apos;s five integrated works.Typically solid raw materials include, iron ore, coal, limestone, ferro alloys and scrap. Intermediate products such as coke and sinter create their own specific handling and wear problems.Coals and ores are shipped into the United Kingdom from several sources, and have a great variety of properties. Some coals can be extremely wet and sticky, whereas others are dry and dusty . The ores handled can vary from wet concentrate and fines to heavy angular rubble and pellets. These raw materials are off-loaded, stored and conveyed through British Steel&apos;s own port facilities at Port Talbot, Immingham, Redcar and Hunterston. British Steel also produces the majority of its own coke and all its own sinter. Coke and sinter are frequently handled at elevated temperatures which cause other handling problems."

Jan 1, 1991

By C. J. Newman, D. J. Kemp, R. M. Sweetin

"The smelter is described by area; feed preparation, continuous furnace line, gas handling and auxiliary systems, blister refining, Hazelett casting of thin anodes, and scrap remelting. Early smelter campaign data is presented and compared to design. Some modifications to the basic design of the furnaces and gas trains are indicated, with their respective impacts on improving smelter performance.Plant compactness, the use of jumbo tanks, and a highly automated electrode handling system are featured in the refinery description, with brief coverage of the liberator and slimes leaching sections. Early experience in refining thin regular Hazelett anodes, and submersible pump recovery of raw slimes are relayed, together with automatic stripping from titanium blanks.Refinery tonnages and operating parameters are given showing the relatively trouble-free attainment of refinery design performance.IntroductionPrevious papers and articles ( 1), (2) ,(3 ) have described the metallurgical facilities serving the copper-zinc-silver Kidd Creek orebody located near Timmins, Ontario. For convenience a brief review of their mid-1983 operating status is presented.The concentrator, originally designed for 9,000 short tons, was commissioned in late 1966. It can now comfortably process over 13,000 metric tonnes per day largely as a result of the addition of a fourth circuit in 1978."

Jan 1, 1984

"Mining with blast holes drilled upwards may be done to recover sill pillars, or for economic reasons when the distance between the levels is relatively large. If the rock is sufficiently competent to accommodate large stope size, the distance between sublevels could be increased to as much as drilling accuracy allows. The same drill drift can be used for the drilling of both down holes and up holes. In the case of down holes, the initial opening of the stope (drop raise) is not as much a problem as for the inverse drop raise for mining with up holes. This is because, with a drop raise, a lot of space is available at the toe for the blasted rock to expand. In addition, the raise can be blasted in many shots, thus allowing smaller blasts each time. Inverse drop raises are generally much more difficult to blast because of the limited space for muck flow, and must, therefore, be taken down in a single blast, requiring special considerations in order to ensure a success. A case study of a 29 m (95 ft) inverse drop raise successfully blasted in a single shot at Heath Steele Mines is described. The paper covers technical considerations such as drilling accuracy, hole deviation survey, delay extension and protection, initiation methods and initiation sequence. Finally, a novel method for creating the initial opening called ’slot drilling’ is presented. This method, inspired from LKAB in Sweden, consists of drilling a row of interconnected holes using a special guide mounted on a regular production drill hammer.With a case study of blasting an inverse drop raise of 29 m (95 ft) in one blast, this paper further discusses some technical issues that are critical for the development of inverse drop raises. A novel method for creating the initial opening with a slot of interconnected holes is also presented with the experience acquired at different mine sites across the Noranda group."

Jan 1, 2000

By Kai Zhang, Aijun Huang, Jeremy H. Rao, Xinhua Wu, Paul Rometsch

"As one of the most typical additive manufacturing (AM) technologies, selective laser melting (SLM) removes many of the shape restrictions that limit materials design, thereby allowing computationally optimised and high performance structures to be directly produced and tested. Due to the high reflectivity and lower absorptivity of Al alloy A357 powder during high temperature laser melting, one of the issues SLM might bring is the surface roughness and defects present on the parts. In this regard, this study investigates the surface roughness – fatigue property relationship for a heat-treated aluminium alloy A357 after SLM. Via the adjustment of SLM parameters, an ultrafine microstructure can be obtained due to the fast solidification rate. Therefore, comparable or even better mechanical properties can be achieved with respect to traditional A357 casting counterparts. Meanwhile, the surface roughness conditions of the SLMed Al alloy are also influenced by various processing parameters, raw powder properties, and sample building methods. For selective laser melted Al alloy A357 specimens, a dense part with a smoother surface would be expected to correspond with a good fatigue performance.INTRODUCTION Additive Manufacturing (AM), also known as 3D printing, is a process in which a complex part is fabricated layer by layer from a digital design package (Martin et al., 2017). AM has the potential to conserve raw materials, reduce the energy consumption, part cost, and fabrication time. Furthermore, as a typical additive manufacturing (AM) process, selective laser melting (SLM) was originally developed from selective laser sintering (SLS) based on higher quality lasers (Rao, Zhang, Fang, Chen, Wu, & Davies, 2017b). Different from conventional casting consuming valuable time and energy, SLM is now used as a cost effective method for the manufacturing of metals, such as Al-Si alloys, to produce almost full density parts using fine metallic powder and high power laser beam (Tang & Pistorius, 2017)."

Jan 1, 2018

By V. I. Peresypkin, A. Y. Lein, N. S. Bortnikov, Yu. A. Bogdanov

"Abstract - The lipid component in hydrothermal deposits of the Logachev vent field, at 14°45_N of the Mid-Atlantic Ridge (MAR) and Broken Spur vent field, at 29°N of the MAR, was studied. Biochemical, gas chromatographic (GS), and molecular mass methods (GC-MS) research established the mixed nature of the organic matter (OM) including phytoplanktonogenous, chemosynthesized lipids, and lipids of questionable origin. Specific local conditions around the sulfide ores of the black smokers (absence of free oxygen and presence of reduced copper, which prevents OM degradation) facilitate the preservation of biogenic material, including bacteria. The main differences between the lipid compositions of the hydrothermal deposits of these two vent fields relate to the variable nature of hydrothermal circulation systems.At the 14°45_N vent field, high-temperature hydrothermal fields are forming due to the reaction of sea water with upper mantle ultrabasic rocks during serpentinization (a deep hydrothermal circulation system). High pressure and temperature (>400°C), a reducing environment and the presence of various metal oxides are favorable for the abiogenic synthesis of CH4 and oil hydrocarbons (HC). At the Broken Spur vent field, hydrothermal deposits are forming above axial crust magma chambers due to the interaction of sea water and basalts (an axial hydrothermal circulation system). Abiogenic synthesis of HC also occurs in this situation, but to a considerably lesser extent."

Jan 1, 1999

By Hajime Miki, Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, A. M. Elmahdy, Keiko Sasaki

"Seawater has been reported to depress molybdenite in a copper-molybdenum (Cu-Mo) flotation process at high pH due to the precipitation of Mg(OH)2. Meanwhile, to improve mineral recoveries, collectors are usually added into the flotation cells, thus adding the complexity to the mechanism of bubble-particle interactions involved in Cu-Mo flotation. Therefore, understanding the interaction mechanism in seawater flotation and in the presence of collectors is important to explain the minerals depression. The present work investigated the effect of kerosene on the bubble collision and attachment to pure chalcopyrite and molybdenite surfaces in MgCl2 solution as one of the seawater major components at pH 6 and 11. Mineral surfaces were characterized using atomic force microscopy (AFM). In addition, minerals floatability in the same system were tested in a column flotation. The study of bubble-particle interactions shows that following several collisions, bubble could displace the intervening liquid layer on the mineral surfaces, forming a three-phase contact (TPC). A TPC formed more rapidly in the presence of emulsified kerosene in a 0.01 M MgCl2 solution at pH 6 for both minerals. The reason is kerosene increased the surfaces hydrophobicity and destabilized the intervening liquid layer on the surfaces. Moreover, the average time required to form a TPC was shorter on molybdenite surface. This can be attributed to the effect of adsorbed kerosene on molybdenite surface and molybdenite surface roughness.INTRODUCTIONIn froth flotation, bubbles are used to separate hydrophobic mineral particles from hydrophilic particles. In this process, bubble-particle interactions (i.e., collisions, attachment, and detachment) are crucial with regard to mineral recoveries. The effectiveness of froth flotation depends on the formation of stable aggregates between the hydrophobic particles and the bubbles, allowing the bubble to carry the particles to the froth layer. To form such aggregates, the bubbles and particles must collide, and the intervening liquid layer must be drained below the liquid layer critical thickness, forming a stable threephase contact (TPC) (Ralston & Dukhin, 1999). Particles detachment may take place if the particles still have sufficient kinetic energy and the TPC is not formed. Previous studies of bubble-particle interaction in electrolyte solutions have been conducted using atomic force microscopy (AFM) (Assemi, Nguyen, & Miller, 2008), and by approaching the bubble using mica plate (Pushkarova & Horn, 2008), however, these studies did not focus on the bubble-particle collisions. Bubble collisions and attachment to hydrophobic (Teflon) and hydrophilic (glass) surfaces in a a-terpineol solution have been investigated by Krasowka et al. (2003)."

Jan 1, 2016

By C. W. Jr. Waterman

INTRODUCTION MY SUBJECT is one which would require several speakers and many hours of time for adequate presentation in all its many facets. Because of the widely varying market requirements and coal seams mined, the coal industry of the United States bas of necessity employed many types of preparation facilities to satisfy its needs. Predominance of Baum-type jigs, however, bas marked the mechanical cleaning installations since the early thirties, and these machines continue to hold the lead. CLEANING As a matter of record we find that, at the end of 1948, we had 480 mechanical cleaning plants in operation. Of these, 19 used air cleaners only,?400 used water washers only, . and 61 used dry and wet washers in combination . Due to the increased use of spray water underground on cutting and mechanical mining equipment, there has in recent years been a marked downward trend in dry cleaning installations. In fact, the moisture in dry-cleaned fines has been increased to such an extent by spraying that recent dry cleaning installations have incorporated thermal drying ahead of the dry cleaning units in an effort to overcome the varying and increasingly higher moisture percentages in their raw coal feeds. While on the subject of dry cleaning, it might be well to bring to your attention one of our most recent developments in this art. I refer to the McNally-Brusset vacuum jig.

Jan 1, 1951

This paper generalizes open stopes into elliptical cross sections and applies the results of calculations based on the mathematical theory of elasticity to indicate stress distribution on the boundaries of such stopes. These show both compressive and tensile stresses and provide an ex-planation for the development of excessive dilution in shrinkage toping. Introduction T HE stress pattern around shrinkage stopes is identical with that around other stopes under the same physical conditions. However, a shrinkage stope ends as an unsupported open stope, and the method i limited to the stress range within which the rock is generally self-supporting. If it is acceptable to generalize the outline of a shrinkage stope into an elliptical cross section, then the graphs of Geldart & Udd (1) (see also Panek (2) and Denkhaus (3)) provide a good base for approximating the stress distribution as mining progresses. However, with failure conditions in the walls, the axis ratio, as cut

Jan 1, 1964

By John L. Bonus

"WITHIN THE BROAD PARAMETERS implied by the title of my speech, I propose to deal more particularly this evening with a subject the many aspects of which have constituted the essential elements of one of the main thrusts undertaken by the MAC in the past two years, i.e., to create among Canadians a much greater awareness of the importance of mining and to demonstrate to them what are the many and varied benefits they derive from mining activities across their country. In other words, MINING - WHAT IT MEANS TO CANADA.I also intend to discuss some aspects of government-industry relationships.I am very conscious of the fact that I am speaking to an audience made u in large part of experts in several fields of mining and exploration activities. They will be familiar with many of the points I intend to discuss. However, without in any way suggesting that familiarity breeds contempt, might I emphasize that even in this particular forum there is justification for reiterating some of our basic philosophies and suggesting ways whereby they might be better understood and promoted.Let us first summarize the present dimensions of the Canadian mining industry."

Jan 1, 1971

By C. R. Kato, G. Proulx

"Within the continuous scenario of reduced aluminium price and plants production costs increase, the energy consumption optimization in the aluminum electrolytic pots continues as the main focus for the producers. Energy consumption was chosen as a key performance indicator to drive the efforts and actions for improvements. Alcoa improved the energy consumption by approximately 3% from 2005 to 2015. This improvement was a result of best practices implementation, new technologies introduction, strategic actions with plant curtailments and management practices. The main objective of this paper is to highlight the importance of the management practices for planning and operational improvements beyond the technology changes. About 10 years ago, Alcoa reorganized its approach to retain knowledge in the Smelters by using a Best Practices format. For each specific subject, a skilled team defined the minimum requirements and the Best Practices for several aspects of operation and maintenance, which affect the environment, safety, cost, customers and performance. These Best Practices were deployed to all Smelters combined with training sessions to process and operation professionals. We will describe how the Best Practices were organized, the deployment strategy used, and the approach to measure the plants’ success. We will describe the management approach that includes Manufacturing Analyses focused on 3-year potential, annual planning, and weekly monitoring of plant stability. A manufacturing analysis is organized at select plants with cross-functional participation of specialists from technical, operational, procurement and finance. The output of a manufacturing analysis includes a roadmap of enablers to improve energy efficiency. A quarterly follow-up of enabler deployment is held with the plant and resources that participated in the analysis. Annually, there is a Planning Process where energy consumption enablers are selected to be implemented during the next 3 years for each plant. A monthly critical analysis is made by the plants with regional best practice support. On a weekly basis, key performance indicators are reviewed with determination of a stability index for each plant. Any deviation signal of unstable condition is alerted and supporting resources are diverted to the plant to reverse trend with countermeasures.INTRODUCTIONDue to factors like excess aluminum in the market and lower consumption in China, the LME price is declining along the last years, as showed in Figure 1. In 2011, the price peaked at US$ 2,400/ton and since then, continues to trend down and approaching the lowest level at US$ 1,500/ton in the last 5 years."

Jan 1, 2016

By P. H. Agson Gani, T. Sitorus, N. P. Widodo

"PT ANTAM UBPE Pongkor underground mine use blasting to develop its tunnels which will cause poisonous and dangerous gases trapped inside mine. To analyze this case, a study of mine ventilation, the dispersion of carbon monoxide (CO) gas concentration and diffusion coefficient is commenced. At the end, the re-entry time formula will be determined. Results indicate that this study is site specific and could only be applied in the place this study executed. The aim of this study is to be further developed by applying Principal Component Analysis (PCA) to find a universal re-entry formula. KEYWORDS Mine Ventilation, Re-Entry, Smoke Clearing, Diffusion Coefficient, Carbon Monoxide Gas, Gas Dispersion INTRODUCTION Pongkor underground mine is using cut and fill as its mining method. Thus, its development and production processes require blasting to develop its tunnel. This process caused poisonous and dangerous gases spread and trapped inside the mine, one of them is carbon monoxide (CO) gas. CO is formed in an unbalanced reaction of explosives detonation and could be the cause of headache, blackout and death to people who inhale CO at certain concentration (McPherson, 2011; Hartman, Mutmansky, Ramani, & Wang, 2012). Mine ventilation system is installed in the mine to resolve this problem. Mine ventilation play an important role to disperse CO gas by absorb the poisonous/dangerous gases and deliver clean air into mine. The important parameter is diffusion coefficient, because diffusion is affecting particulates or gasses spreading from its sources throughout the mine. Diffusion coefficient is the total diffusion in axial direction of turbulent flow mainly by convection of bulk motion, advection and eddy diffusion, while the effect of molecular diffusion is appreciably negligible (Widiatmojo et al, 2015). Taylor (1953, 1954) develops a theory about the dispersion by inducing a slow stream of solvent into a capillary tube. Taylor used Reynolds assumption of radial diffusivity to be analogous with the transfer of the matter in turbulent flow as well as the transfer of momentum and heat. Then, Taylor proposed the formula of diffusion coefficient, D (m2/s), against pipe diameter and turbulent shear velocity are as follow:"

Jan 1, 2019

By F. E. Millett

The following notes deal chiefly with changes from steam to electric drives, or, in the case of the Bellevue pumps, from air to electric. Where electric power can be purchased or generated cheaply it can be used to advantage and is generally more economical than steam, especially in places remote from the central power-plant. Nothing could be more simple than the operation of electrical gear. It does not require a competent engineer constantly on the alert, oiling and watching bearings, and maintenance is at a minimum. The ease with which the current is transmitted from its source to where it must do its work is one of its greatest advantages. Transmission losses are very low. Generally speaking, the smaller the plant the lower the loss and 90 per cent, and better, efficiency is easily attained. In and around Bellevue 2300-volt, three-phase, is the standard distributing pressure; our power requirements and the distances transmitted, for the present, do not require more than this. Most of the heavier motors are 2300-volt .machines, which eliminates the cost and possible troubles of step-down transformers, and makes for a cheaper and less bulky motor. This applies to two fan, two hoist, and two compressor motors, the smallest being 75 and the largest 520 horse power. The standard pressure on power lines to all inside pumps is 550 volts, and 220 volts is general for the the tipple. While 110 volts is used for house and office lighting service, it is not economical around and in the mine. No matter what kind of device is used to lock and protect the lamps, they are invariably missing.

Jan 1, 1926

By R. Le Houillier, M. Nagamori, A. J. Plumpton

"Asbestos tailings are a typical serpentine, hydrated magnesium silicate, consisting primarily of antigorite and a few per cent of unrecovered fibrous chrysotile. Serpentine has unique thermal properties in that dehydroxylating calcination at 600 to 700°C can yield an amorphous structure in which most of the magnesia is liberated from the original bond with silica and thereby rendered chemically active. The amount of activated magnesia can be quantified by selective leaching with a weak acid such as acetic acid. Many wet processes have been proposed to extract magnesium values from calcined or natural serpentine by means of various acids and their ammonium salts. However, the only commercial utilization of serpentine today is found in dry processes such as the production of fused magnesium phosphate fertilizer .The present paper reviews the physical chemistry of the dehydroxylation of serpentine and also various wet and dry processes in order to provide a general view regarding the chemical transformation of asbestos tailings.IntroductionAsbestos fibers occur as chrysotile, a serpentine polymorph. More than nine tenths of mined asbestos ores consist of massive non-fibrous serpentine, primarily the polymorph antigorite, which is discarded as tailings after fiber extraction. For many decades, Quebec has been a world leader in the production of asbestos fibers. As a result, colossal tonnages of serpentine have accumulated in the Eastern Townships&apos;!&apos;. Serpentine minerals are found in large deposit s throughout the world, and significant research efforts have been made, particularly in Japan and the USSR, mostly in attempts to extract magnesia or silica values therefrom.The chemical composition of serpentine (chrysotile and antigorite) may be ideally expressed as Mg3Si2Os(OH). which corresponds to 43.7% MgO and 43.3% SiO2. Natural serpentines often contain a few per cent of Ni-bearing magnetite and other impurities, and therefore the contents of MgO and Si02are both about 40% or lower.Serpentine (hydrated magnesium silicate) is virtually insoluble in weak acids. However, when dehydroxylated under controlled conditions, &apos; it decomposes to an amorphous state in which magnesia and silica are isolated and chemically active. The magnesia so activated is readily soluble in weak acids. This unique characteristic of calcined serpentine, first discovered in 1942,, has since attracted the attention of innumerable researchers, whence many processes have been proposed."

Jan 1, 1980