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By Masami Hayashi

The Bureau of Mines conducted laboratory studies to investigate methods for desilicating sodium aluminate solution derived from leaching a limestone-anorthosite sinter with 10-pct Na2C03 solution. Desilication tests were made at atmospheric pressure to determine the effects of time and additions of lime and desilication residues. A two-stage, countercurrent desilication procedure was developed to reduce the Si02 content sufficiently to meet specifications for cell-grade A1203. Both stages were conducted at boiling temperatures at atmospheric pressure. Reagent lime was charged as desilication seed to the partially desilicated solution in the second stage, and a product (desilication residue) precipitated by the lime addition was charged to the freshly leached solution in the first stage. Average A1203 loss in the desilication circuit was 5.8 pct, and the product solution contained less than 0.04 g/l Si02. Complete precipitation of A1203 by carbonation resulted in a hydrate containing less than 0.01 pct Si02. Calcination of this hydrate would produce A1203 meeting the 0.015 pct Si02 specification for cell-grade material.

Jan 1, 1982

By C. A. Young, J. D. Miller

Thermodynamic data has been obtained for oleate chemisorption at fluorite (CaF2) and calcite (CaCO3) surfaces using adsorption isotherms determined previously at room and elevated temperatures by in-situ Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS). Linear regression analysis was used to statistically derive free energy data as a function of temperature assuming oleate chemisorption followed Langmuir-type adsorption. Enthalpy and entropy changes were subsequently ascertained from the Clausius-Clapeyron equation and fundamental thermodynamic relationships. Essentially, no difference in the free energy of chemisorption at the two mineral surfaces was found; however, the differences in enthalpy and entropy values were significant. By comparison, the results showed that oleate chemisorption at fluorite surfaces was more extensive and more entropically driven due to more water being displaced. Results correlate well with values determined in the literature for other mineral collector systems. These findings help explain the greater hydrophobic character of fluorite than calcite in both the absence and presence of oleate.

Jan 1, 2002

By G J. Lyman

In sampling a process stream, conventional sampling theory deals only with the variation of the analyte content and neglects the impact of the variation in the mass flow on the sampling variance, whether the sampling regime is time-based or mass-based. This is an obvious simplification of the real state of affairs and it is worthwhile to study this impact via simulation.With a facility to simulate large (long) random functions having some thousands of points in the function and the ability to impose covariance functions on the mass flow and analyte variations, such a study is possible. It is also possible to evaluate the impact of correlation between analyte content and mass flows.This paper describes a limited study of the variance increase due to mass flow fluctuations over the usual sampling variance due to analyte variation during the sampling period. The bias in the sampling result is determined for specific modes of correlation. Simulation methods are used as they are the only means by which a sampling result can be compared to the true assay for the lot; in the physical circumstances of mineral process analysis, it is never possible to determine the true process stream assay.CITATION:Lyman, G J, 2017. The impact of the weighting error, in Proceedings Eighth World Conference on Sampling and Blending , pp 311–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Peter Fischer

Reducing mining costs has become such an important factor in the German coal industry that operators are forced to work only those areas where production costs can be kept low. These areas will normally be located close to the mine shafts because they are easily accessible. Even the shaft pillar is now being considered as part of the winning zone. Before working coal in shaft pillar zones it is essential to assess the impact this will have on the shaft lining. There is a huge difference between sliding and strata-anchored shaft systems. However, if the overburden comprises lightweight soil both types of shaft will have a tendency to protrude from the surrounding ground. This paper presents the geomechanical reasons underlying this reaction and the methods used for predicting and measuring it.

Jan 1, 2007

By Dippenaar R, Evans T

Twin-roll continuous casting technology is rapidly approaching commercialisation. Fundamentally different than conventional continuous casting, heat transfer and hence solidification during twin-roll casting are governed by the interfacial melt/mould thermal resistance, as opposed to the resistance of the solidifying shell. Under these conditions the interface resistance is predominantly controlled by the melt/substrate wetting behaviour. The very early stages of melt/mould contact are characterised by highly transient heat transfer conditions. The overall melt cooling rates prior to the formation of the first solid are reported to be in the range of 1000 - 50000 K/s with melt undercoolings of up to 300 K. At the points of intimate melt/mould contact the thermal resistance is approaching zero, where cooling rates and undercooling much larger than those reported in the literature are probably occurring. Improved wetting will reduce the energy barrier for nucleation while at the same time increasing the cooling rate of the liquid. Since the overall nucleation rate is controlled both by the rate of cluster formation and the rate of atom transfer to the nucleus, a critical cooling rate will exist above which the nucleation rate is expected to be reduced. Under these conditions, it is possible that the first solid phase to form is a metastable glass which subsequently transforms into a crystalline phase. The implications on nucleation and early growth are also discussed.

Jan 1, 1999

By M. A. Reyes, L. Yan

Heat and humidity buildup within refuge alternatives (RAs) may expose occupants to physiological hazards such as heat stress. The Mine Safety and Health Administration (MSHA) regulations require RAs in underground coal mines to provide a life-sustaining environment for miners trapped underground when escape is impossible. RAs are required to sustain life for 96 h while maintaining an apparent temperature (AT) below 95 °F (35 °C). The National Institute for Occupational Safety and Health (NIOSH) tested a 10-person tent-type RA, a 23-person tent-type RA, and a 6-person metal-type RA in its underground coal mine facilities to investigate the thermal environment over a 96-h period. The test results showed that mine air and mine strata temperatures surrounding an RA occupied by simulated miners (SMs) increased over the 96-h test period. The test results suggest that RA manufacturers should consider this increase in temperatures when calculating and evaluating RA components during surface and laboratory tests. The findings can equip stakeholders with additional considerations for calculating the interior heat and humidity temperature profiles for occupied RAs not tested in situ

Nov 22, 2019

In responding to why some longwall roadway development rates are different among mines, the Roadway Development Task Group (RDTG) of Australian Coal Association Research Program (ACARP) has initiated a benchmarking study to survey each longwall mine to determine the correlation between roadway development practices and roadway development performances. This paper describes a web-based relational database system which has been developed purposely to monitor the performance of Australian longwall roadway developments aimed at assessing both the physical and operational factors which could influence roadway development practices and their performance indicators. Statistical analysis of an earlier survey suggested that continuous miner units that achieved more than 1750 m were units mining two-heading development.

Dec 6, 2010

By G. Balletto, C. Furcas

"The mineral raw materials industry is a key-component of the Gross Domestic Product of industrialised economies, closely related to both the building and the industrial sectors. Despite this, at local level mining and quarrying are associated with both irreversible environmental damage and several visual alterations affecting the natural landscape. In this sense, SIA (Social Impact Assessment) has become a strategic tool that can not only improve the prediction but also the assessment of the social impact by involving the local communities in a participatory process. Taking into account the SIA experience, together with the examination of some relevant international case studies, it is possible to draw up a list of good practices for mining project management, from exploration through to closure and beyond, with quarry restoration. Such good practices will complement the existing studies, focusing on environmental issues, with the social issues arisen considered in SIA application."

Jan 1, 2011

By Laurence McGonagle

"The Highland Uranium Project (HUP) is located approximately sixty miles northeast of Casper, Wyoming and is owned and operated by Power Resources, Inc. (PRI). With an annual production of680 tonnes (1.5 million lbs) U308, HUP is one of the largest uranium producers by in-situ leach (ISL) in the western world. Uranium is currently produced from four wellfields with a total flow rate of approximately 1,135 m3/hr (5,000 gpm). The carbonate leach solutions are processed by anion ion exchange at two satellite facilities located in close proximity to the wellfields. The loaded resin is transported by truck to a central processing facility for elution of the uranium. Uranium in the pregnant eluant is precipitated and washed prior to calcining.Wastewater from the satellite facilities is treated and used for irrigation at a Land Application Facility. The wastewater generated at the central processing facility is injected into a 2,750 m (9,000 ft) deep waste disposal well.When economical mining of the orebodies is complete, restoration of the groundwater is initiated. There are currently two wellfields at HUP undergoing ground water restoration. Phase I restoration consists of removal of the carbonate leach solution from the ore body. Phase II includes treating the withdrawn fluid with reverse osmosis and reinjection of the permeate into perimeter wells.Future plans include construction of additional satellite facilities at the Gas Hills Project and other economical deposits located within 240 km (150 mi) of HUP. The capacity of the central processing facility will be increased to 1,815 tonnes (4 million lbs) U308 per year by late 1999."

Jan 1, 1998

By Ivor Hawkes

This report describes the results of a study to evaluate new design concepts for percussive rock drills that will result in quieter machines. It is shown that by incorporating such features as an efficient muffler, a plenum chamber integral with the machine body, and shroud tubes around the drill rods, etc., noise levels are reduced from about 114 dBA to about 95 dBA with very little change in drilling performance.

Jan 1, 1977

By J. Stacey

This study was undertaken to generate a locally relevant guideline for the socio-economic aspects of mine closure for South African closure practitioners and decision makers. It should also represent a resource for interested and involved stakeholders. Mine closure, and its related post-closure social, environmental and economic characteristics, is part of the lifecycle of mining operations, given the finite nature of the ore resource. Many coal mines are anticipated to close in the next ten to fifteen years in Mpumalanga, as the epicentre of the industry shifts towards the Waterberg. Social aspects of mine closure have been historically underplayed, and under researched. Coaltech thus commissioned two studies, the first of which examined the closure dynamics of 36 mines in Mpumalanga and KwaZulu-Natal in 2006. A follow-up study (July 2007) focusing on Mpumalanga3,4 confirmed some of the results of the first study. It also contained broad guidelines for mine closure covering social and labour planning, job creation, the use of mine infrastructure, developmental incentives, and environmental rehabilitation.

Jan 1, 2010

By Xi Zhang

A technique for fabricating free-standing, high-aspect-ratio porous and pillar-type Ni structures has been developed using wet Si processing. A wafer of (100) Si was initially etched in HF solution to form deep pores with micron-sized diameter. The aspect ratio can exceed 200. By introducing the as-etched Si into a defined aqueous Ni2+ solution, Ni deposits grew rapidly onto the sidewalls and replaced the Si. Long-time immersion allows the Si sidewalls to be completely converted and thus form a metallic Ni structure with high-aspect-ratio pores. It is known that close-packed submicron Si pillars can be formed by oxidizing and subsequent etching of the macropore sidewalls. Treated in the same Ni solution, high-aspect-ratio Ni pillars were correspondingly emerged by replicating the original pillar-type Si structure.

Jan 1, 2006

By Raja V. Ramani

The potential usefulnuss of reclaimed surface-mined land has received much attention in recent times. This attention is partially due to the establishment of federal environmental reclamation standards but concern for achieving better land uses has also been shown by interested members of the mining industry. In an effort to develop a procedure for evaluating postmining land use potentials, specific mines in various regions of the U. S. were studied to determine the extent of current mined-land planning and to discover characteristics that are regional in nature. As part of this investigation, a 430-acre surface mine in Clear-field County, Pennsylvania has been studied. Established site planning principles have been applied to the case study site including formation of a data base, development of alternate land use plans, and evaluation of the economic, environmental, and social impacts of the land use alternatives. Key factors affecting site realization have been identified along with positive suggestions for applying land use planning processes to mined-land planning.

Jan 1, 1983

By Scott C. Brown, Ivan U. Vakarelski

The particles commonly encountered in mineral benefication schemes have irregularites that are expressed at many different length scales. In part, this originates from preceding processes (e.g. makedown, comminution, handling and storage), which are known to chemically and physically modify the bulk particle and its surface. Interparticle tribology, dissolution and reprecipitation events along with large-scale mechanical stresses are just a handful of the interactions encountered during processing of particles prior to separation. It is feasible to imagine that each one of these events may impose a fingerprint of characteristic nanoscale, microscale, and macroscale morphological changes that can modify the overall interaction of these particles within a system. Suprisingly there are just a few works on how these resulting features can alter the performance of benefication schemes, and especially flotation.

Jan 1, 2003

By E Villaescusa, C Drover

Fully resin encapsulated threaded bar and cement grouted cable bolts are common forms of reinforcement for underground mining excavations constructed at great depth. These elements are frequently installed to dissipate the dynamic loads caused by violent rock mass failure mechanisms. Failure of the ground support scheme without rupture of the reinforcement elements implies that the maximum energy dissipation capacity of the scheme was not utilised. The ground support damage mechanisms are useful to identify in this context as they reveal vulnerabilities which limit the scheme performance. This paper presents a number of field observations of reinforcement performance following a range of dynamic loading conditions. It was observed that fully resin encapsulated threaded bars exhibit variable behaviour. In particular, inconsistent resin encapsulation was frequently observed in combination with surface support failure, indicating that the retention function of these elements may allow preferential loading of the surface support system. Observations of cement grouted, twin-strand plain cable bolts reveal a common mode of damage involving differential displacement across the steel-grout interface and slip of the cable within the borehole. This is common where strands are not mutually tensioned with barrel and wedge assemblies. Surface fixtures that exceed the strength capacity of the cable strand are required in order to minimise the occurrence of this response. Improved load transfer from the rock mass and surface support to the cable can thus be achieved, particularly where small block size failure occurs.CITATION:Drover, C and Villaescusa, E, 2016. Field performance of fully encapsulated reinforcement during violent failure events, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 659–668 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By T. Güyagüler, A. Güngör

Labour protection, that is prevention of occupational disease and reduction in the frequency of accident, has always been a matter of major concern of mining industry. Management and the government should promote and maintain high safety standards through some measures to reduce accident frequency and occupational disease. This can be achieved by using the science and technology for improving the working conditions, educating workers and managers about accidents and prevention techniques. The detailed analysis of an accident requires knowledge of many factors such as location, time, type, cost of accident, victim, nature of the injury, personal and environmental factors etc. that can be obtained from the standard coded accident report form. There is a need to prepare safety data in a common format to produce a common safety reporting system and ‘Occupational Health and Safety Management Tool’ is being designed to manage this by using database and Internet technology. Precautions should be taken according to results from database queries by providing comprehensive and accurate national data. To have an accident is unfortunate, however, to have an accident and learn nothing from it is unforgivable. Keywords: Occupational health and safety, Accident report form, Accident database, Occupational diseases and accidents, Safety reporting system.

Jan 1, 2003

By Evans E. C.

At first sight, the extinction of a mine fire by the action of some such gas as carbon dioxide would appear to be quite a simple and practicable operation. From a consideration of the theoretical aspects only of the question, it becomes evident that the matter is not so simple as it appears to be at first sight. The fire at the Senghenydd Colliery occurred as the result of the disastrous explosion of October 14th, 1913. This explosion was confined to the west side of the colliery; and as a result the timbers in the main intake on this side were set on fire; but these were soon buried beneath falls, and the tire continued under them. Attempts were made to extinguish it with water, with the aid of chemical extinguishers, and by digging it out; hut these had to he abandoned, and ultimately the fire-zone was sealed off by “ bashings” (stoppings). By December, progress in the decrease of combustion was so slow that it was decided to try the effect of inert gas. The installation, control and operation of the carbon dioxide plant and associated water-gauge are described in detail and conclusions drawn for the extinguishing of mine fires by CO2

Dec 1, 1916

By J. Patterson

"Acid Mine Drainage (A.M.D.) formed from oxidation of disposed pyritic wastes presents a potential pollution hazard for Equity Silver Mines Limited and the mining industry in general. Failure to collect and treat these acidic effluents can eventually affect the quality of receiving streams and endanger aquatic life forms. Treatment and discharge of A.M.D. to the receiving environment must comply with stringent anti-pollution laws.Wastes mined at Equity Silver Mines Ltd. are predominantly acid generating and must be handled according to a materials management plan to minimize impact on the environment. Effluent collection and treatment facilities have been constructed to address the short term environmental concerns with reclamation and research programs being developed to address and monitor abatement measures for control over the long term.The purpose of this paper will be to offer a brief overview of these measures. Key topics for discussion will be: kinetics of Acid Mine Drainage, acid generating potential, water treatment and sludge handling, special wastes, waste dump construction, waste rock amendments, bacteriocide research, simulations, and reclamation measures. Programs designed to evaluate impact on the receiving environment, although they form an extensive part of the program, will not be discussed in this paper.INTRODUCTIONEquity Silver Mines Limited is located in the Central Interior of British Columbia, within the Omineca Division, 35 kilometers southeast of Houston Mining and approximately 575 kilometers by air north-northeast ofVancouver (Figure 1).The deposit consists of three economic mineralized zones: The Southern Tail, Main and Waterline Zones. Mining of the Southern Tail commenced in April, 1980 and was completed in the first quarter of 1984. Main Zone production was initiated during the last quarter of 1983 and the Waterline Zone remains undeveloped to-date. Remaining reserves are in the order of four years contingent on favourable metal prices. The three deposits (Figure 2) occur within a window of interbedded volcanic and minor sedimentary rocks. The older volcanic sequence is bounded on the west by a small granite-like stock and on the east by a gabbro-monzonite complex. All are overlain by a series of younger lava flows."

Jan 1, 1988

By Richard C. Banting

Excessive vibration is known to have an adverse affect on soft body tissue and operators of heavy mining equipment can be exposed to vibration that exceeds levels recommended in international guidelines (ISO 2631-1, for example). Research has found that many of the seat and suspension systems currently used in mine haul trucks and load haul dump vehicles are actually amplifying the vibration. This overview presentation will outline the current research being conducted at Laurentian University and the University of Western Ontario, and the roles of partners in rating the ability of a number of commonly used mine vehicle seats to isolate harmful vibration.

Oct 1, 2010

By Kristie Tarr

Portland cement is primarily used to solidify backfill in underground mine workings and it represents a major cost in mining operations. CANMET-MMSL has invented an alternative binder technology that does not contain any amount of Portland cement and is made using waste materials, such as development rock and smelter slag. The technology has been successfully tested with many types of base metal and ferrous slag. Research conducted in collaboration with several mining operations in Canada has shown that the CANMET-MMSL binder has considerable potential as a replacement for Portland cement in mine backfill. An integral part of the overall mining operation, backfill is used for two main purposes: safety and environmental remediation. Depending on the mining method used, backfill provides a working surface, stabilizes stope and pillar walls, as well as the surrounding rock mass, and controls caving of stope backs. There are several benefits associated with the replacement of Portland cement in backfill, including reductions in (i) the footprint by placement of slag waste underground, (ii) the environmental effects and long term liability resulting from disposal and containment of slag waste on surface such as acid rock drainage, (iii) GHG as a result of reduced Portland cement usage (the production of 1 ton of Portland cement produces 1 ton of GHG), and (iv) the significant costs associated with reduced Portland cement usage.

Oct 1, 2010