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By G A. Wellwood

What do all iron ore mines have in common? Perfect production days! Yes, those harmonious 24-hour periods when the stars align and the daily output number rockets past the long-term average to hit new heights. While perfect days are always welcome, the focusing question iswas that just a ‘flash in the pan’ (due to a special cause) or an indication of the process’s capability (with clues to the common causes) which, if addressed, could make every day perfect? In the context of today’s operating environment, with the need to maximise productivity at minimum cost, it’s an important question.Investigations reveal that the throughput difference between a perfect production day and the average is often in the order of 40 per cent, and that bulk solids handling (BSH) system deficiencies are the largest (>50 per cent) class of lost opportunity. Root causes for underperformance of elements in BSH systems can often be traced back to the detailed design and even study-stage oversights. Essentially baked into the fabricated plant, operations are effectively forced to accept them at the point of practical completion and then deal with the consequences for the life of the mine. Subsequent normalisation of these defects in the planning process reduces visibility and hence the impetus for long-term solutions in favour of lower targets and quick fixes to keep the show on the road. On an industry wide basis the design processes and assumptions responsible for BSH system underperformance become enshrined as common practice and hence repeated across sites and organisations.In addition to making the case for action, practical steps that can be taken to help realise the significant productivity prize and avoid the problems in first place are provided.CITATION:Wellwood, G A, 2017. One perfect (production) day – a bulk solids handling perspective, in Proceedings Iron Ore 2017, pp 443–452 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Forrest T. Moyer

All general measures of the safety record of the coal mining industry worsened appreciably in 1970. Injury experience for the year was 260 fatal and 11,552 nonfatal injuries at respective frequency rates of 1.00 and 44.40 per million man-hours of worktime. The fatality total was 57 higher and the rate of occurrence was 18 percent higher than the corresponding figures of 203 fatal injuries with a frequency rate of 0.85 in 1969. The worsened fatality record in 1970 resulted primarily from a major disaster (a single accident which results in the death of five men or more) on December 30, 1970, that killed 38 men. There were no major disasters in 1969. The total of 11,552 nonfatal injuries in 1970 was the highest annual total since 1960. It was 1,635 higher and the frequency rate was 6 percent higher than the corresponding totals for 1969 of 9,917 nonfatal injuries occurring at a rate of 41.76. The injury severity rate of 8,308 days lost or charged per million man-hours was 13 percent worse than that of 7,359 in 1969. Similarly, the average severity of 183 days lost or charged per injury in 1970 was 10 days or 6 percent higher than in 1969. Aggregate worktime of 260.2 million man-hours and production of 609.8 million tons in 1970 were, respectively, 10 and 7 percent higher than in 1969. An average of 144,480 men were at work on an average of 227 active days in 6,316 mines and 544 mechanical cleaning plants during 1970.

Jan 1, 1973

The current methodology to design stope support systems in South African gold and platinum mines is based upon the tributary area concept. The discontinuous nature of the hangingwall rock is not adequately addressed, and mechanisms leading to rock mass failures between adjacent support units are poorly understood. The work reported here aims to formulate a basis for quantifying support mechanisms and gain insights into the influence of rock discontinuities on stable hangingwall spans. Numerical models are used to qualitatively investigate the stress transfer from the support units to the discontinuous hangingwall. Stable hangingwall spans are quantified by considering two failure mechanisms, namely (i) beam buckling, and (ii) shear failure due to slip at the abutments. The output of the proposed design methodology is appropriate site specific support spacing, based on discontinuity spacing and orientation. The method is particularly suited to mines at intermediate and great depth, where typically the hangingwall is highly discontinuous due to face parallel mining induced fractures. Results of parametric studies show that with increasing in situ compressive hangingwall stress, beam thickness and friction angle, hangingwall stability is increased, leading to wider stable hangingwall spans between adjacent support units.

Jan 1, 2000

By Joseph M. Kurtak

The Bureau of Mines is currently conducting a four year mineral assessment of the 5.7 million acre Valdez Creek Mining District in Southcentral Alaska, as part of its ongoing statewide mining district evaluation program. This report is a summary of the 1987 field work, which included the examination of mines, prospects, and mineral occurrences in the study area. Placer gold has been the most important metal produced in the area, and production totaled 161,131 oz, with the majority of the production coming from the Valdez Creek Mine. Lode gold and silver production totaled 1,581 oz and 8,617 oz, respectively and came mainly from the Golden Zone Mine. Varying amounts of other metals, including copper, lead, zinc, molybdenum, antimony, chrome, nickel, cobalt, tin, tungsten and platinum exist in the study area. Occurrences of industrial limestone and coal are also located in the area.

Jan 1, 2011

By Detnet Solutions

1. “Daisy-Chain” concept The term “daisy-chain” stems from the fact that when the HotShot? detonators are connected there is a chain or electrical path for electrical current to flow from detonator A to detonator B, detonator B to detonator C etc until the path is terminated by an electrical means. The “daisy-chain” concept has long been used in electronic detonator systems, historically used in Expert Explosives’ ExEx 1000 5/6 wire system and currently in use in African Explosives Limited (AEL’s) Electrodet? electronic detonator system and has been adopted as the basis upon which the “auto-programmability” of the HotShot? electronic detonator system functions. HotShot? Detonators are connected to each other in a string, completing a “daisy chain”, and during the auto-detection mode of the control equipment, it is possible for the equipment to determine the order of hookup of the detonators as well as map the entire blast layout. The auxiliary components (Row Controllers & Branch Controllers) assist the control equipment in mapping the entire blast by indicating different points on the blast, i.e. The inflection point of a row of blast holes on a closed chevron timing pattern, the beginning of row of blast holes on open chevron timing pattern and extra blast holes or extra blast rows.

Jan 1, 2004

By I. Nimmo

Since the beginning of Aluminum mining and refining the industry has lived with distributed control rooms and suffered from many behavioral problems common with this design. When Human Factor/Ergonomic design is introduced to a Western Australian installation a common centralized control room realized many improvements including economic payback. Communications issues were resolved, better coordination of materials, improved situation awareness during startups, abnormal operations and an opportunity to make improvements during normal operations characterize the changes at the Worsley Refinery. This presentation will review the reasons for the change. Since the beginning of Aluminum mining and refining the industry has lived with distributed control rooms and suffered from many behavioral problems common with this design. When Human Factor/Ergonomic design is introduced to a Western Australian installation a common centralized control room realized many improvements including economic payback. This presentation will review the reasons for the change, what changed and the process of changing the culture from reactive to predictive and what difference that has made.

Jan 1, 2011

This report presents the results of studies of Kennecott Copper Corporation's tailings embankment at Magna, Utah. The stability studies described were performed on only one cross section of the embankment, utilizing; data obtained from drilling, sampling, and testing, which was limited in nature. The main objective of the data collection was to provide background information to support the overall research effort. Because of this limited scope, it is not possible to evaluate the degree of safety or adequacy of the embankment or disposal system, and the information and data contained in the body of this report must be judged in that light. The first part of this report contains discussion of site geology and seismicity, pertinent information on the refuge disposal system, a discussion of the tailings materials characteristics, a summary of the engineering analyses, and A bibliography. The second tart (appendices) contains basic geologic and engineering data supporting the discussions in the first part of the report.

Jan 1, 1974

By M Maguire

The purpose of this paper is to provide an illustration of the Resource Management Act processes at their best. Many of you will be aware of the Martha Mine situated in the middle of Waihi Township in Hauraki District. Underground mining ceased on Martha Hill in the 1950s. A new mining licence was issued in the late 1980s and since that date open cast mining has continued at the site. The Hauraki District Council notified its proposed plan in October 1994. Prior to that date numerous discussion papers and draft sections of the plan had been disseminated in the community. Considerable consultation was undertaken with all interest groups. As an indication of the success of that consultation process only 17 references to the Environment Court were lodged following the making of decisions on submissions and further submissions. Those references, which included a number from the Minerals Industry, were all resolved by consent. Out of the reference and consent order process EMMA (Extended Martha Mineral Area) was born.

Jan 1, 1998

By G. Norman Owen, Roger E. Scholl

INTRODUCTION The analysis and design of underground structures to resist vibratory motion due to earthquakes has been of interest to engineers for several decades. The dynamic stability of a powerhouse cavern was considered in the 1960s (Campbell and Dodd, 1967). About the same time, the designers of the San Francisco Bay Area Rapid Transit system developed procedures for analyzing the subaqueous tunnels placed under San Francisco Bay and the tunnels excavated along the land portions of the alignment (Kuesel, 1969). Japanese designers developed fairly sophisticated procedures for analyzing subaqueous tunnels during the late 1960s and early 1970s (Kuribayashi et al., 1974). In the past decade, proposals to site important critical underground facilities in regions with moderate to high seismic activity have increased the interest in earthquake engineering of underground structures. Seismic designs or seismic studies have been conducted for rock caverns for storage of petroleum or location of power plants (Yamahara et al., 1977; Glass, 1976), buried tanks for fuels or rad¬ioactive waste (Fukushima et al., 1977; URS/Blume, 1976), tunnels for disposal of nuclear waste (Yanev and Owen, 1978; Wahi et al., 1980), and urban mass transit tunnels (Monsees and Merrit, 1984). One of the greatest drivers of the interest in seismic analysis and design of underground structures has been the proposals to dispose of high-level nuclear waste in mined repositories some 300 to 600 m (approximately 1,000 to 2,000 ft) below the ground surface. In 1979, the authors, in conjunction with Professor Tor Brekke, presented a paper on an evaluation and design procedure used in a study of a proposed nuclear waste repository (Owen, Scholl, and Brekke, 1979).

Jan 1, 1985

By P. J. Watson

The objective of this study was to prioritize the potential risks nuisance and biologically active dusts and fumes present in metal and nonmetal mines. This was accomplished by ranking numerical values derived from a matrix formula calculation that took into account dose, mine population, and sampling size. Data used in these calculations were obtained from the Mine Inspection Data Analysis System (MIDAS). The dusts determined to have the highest risk potential were quartz respirable particulates, mine dust, cristobalite respirable particulates, welding fume components, and nuisance respirable dust. Other dusts and fumes that were not ranked in this study, due to small sampling population, but which show a potential risk, include asbestos, talc, hydrogen cyanide, organic compound dusts, arsenic, metal dusts, and metal and nonmetal fumes.

Jan 1, 1987

By Serge Moalli

The Ashlu Creek Hydro-electric project, located north of Squamish, BC, at the confluence of Ashlu Creek and the Squamish River, comprises a 49 MW run-of-river project and features a 4.08 m diameter, 4.4 km power tunnel and a 128 m deep drop shaft. The Ashlu Creek Hydro-electric project is being developed by Innergex under Ashlu Creek Investments Limited. Site civil works are being completed by Ledcor CMI of Vancouver with tunnel construction by Frontier Kemper Constructors ULC under a lump sum design-build contract. Site works got underway in September 2006 with the construction of the tunnel portal and laydown area. These site works required rock slope stabilization over a 50 m rock slope to secure the laydown area as well as the construction of a tail track muck tipping station and structural wall to facilitate TBM excavation and spoil removal. Starter tunnel construction commenced in early 2007 and TBM tunneling started in the late spring of 2007 and is planned to continue until early 2009. The power tunnel is being excavated using a 1,200 kW Wirth open-type hard rock TBM dressed with 31?17' cutters. The TBM featured two fixed mounted rock bolt drills behind the finger shield: these were removed and replaced with jacklegs to improve access. A probe drill at the end of the main beam is also present. The geology along the 4.4 km power tunnel comprises very strong and generally massive granitic bedrock with rock strength greater than 225 MPa. A unique feature of the project is that no subsurface investigations have been completed for the tunnel however extensive bedrock outcrops are present along the Ashlu Creek valley. A historical quarry exists approximately mid-way along the tunnel alignment that has exposed good quality granitic bedrock. TBM tunneling to date has achieved advance rates of 10?20 m/day with a maximum of 23 m and has encountered all of the anticipated six major fault zones where the installation of various standard high capacity tunnel support was successful to facilitate TBM advance through these sections.

By G. T. Adel, J. D. Miller, C. L. Lin

Washability analysis determines the maximum separation efficiency that can be achieved in the operation of coal preparation plants. Unfortunately, there are no on-line techniques for determining this most fundamental information. It now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. This paper presents the results for the development of a CT-based, on-line coal washability analyzer. The development of appropriate hardware and software necessary to adapt a CT analyzer for use in determining coal washability is discussed. Testing of the analyzer using well-characterized coal samples is presented.

Jan 1, 2000

By K. Oraee

Mining of copper ore and the related industries play an important role in Iran?s economy. Copper ore production in Iran accounts for 75% of the total production in the Middle East. All activities related to copper, that is, exploration, production, refinement etc are owned and managed by state owned companies. Decisions have been made to privatize all these activities. To assess the success of this privatization process, different components of the industry must be subject to economic analysis. In this paper, the cost estimation of all operations has been carried out. The total potential and attainable revenues have also been estimated using historical data available from the industry. Risk is a major factor in all mining activities and the copper industry of Iran has been subject to risk factors arising from many internal and external variables. These variables have been recognized and their effects evaluated. The effect of risk on the economic feasibility of the operations in the industry has also been analyzed.

Jan 1, 2011

By E. Arioglu

Discussion by E. Arioglu Y. Luo and S.S. Peng are to be congratulated for their outstanding paper providing new results from surface subsidence monitoring over longwall panels under different conditions. This writer found the authors' paper very interesting. In reference to this paper, the following contributions are offered: • In the paper, the maximum possible subsidence [(ASmax)] induced by chain pillar convergence has been related to a parameter (h/1- p) by linear regression. (Notations are expressed in this discussion's Fig. 1 (b).) It is a well-known fact that in a goaf the roof lowers onto broken material that gradually compacts. Then the physical behavior of goat may closely follow the compaction characteristics of broken materials. In light of this assumption, a mathematical means (Fig. 1(a)) of defining the expected compaction (i.e. surface subsidence) represents an exponential expression between [ASmax/m vs. h/1-p]. This is based on Luo and Peng's field observations from the Appalachian, Illinois and Alabama coal fields. (The coefficient of regression "r" under consideration was computed to be 0.883). • According to Wardell's (1969) findings for board and pillar mining, the maximum possible subsidence can be expressed in terms of maximum pillar loading (depth, ratio of extraction) and the height-to-width ratio of the pillars left. Using Luo and Peng's 1991 results, this writer discovered a regression equation between the above-mentioned factors. As displayed in Fig. 1(b), the functional expression approximates as closely as possible the observed subsidence data. It may be noted here that Wardell's approach (1969) can be successfully utilized for longwall panels having chain pillars. Reference Wardell, K., 1969, "Ground surface and control," Mining Congress Journal, January, pp. 1-7.

Jan 1, 1993

By Thomas E. Finch

This report is an engineering-economic evaluation of alternate methods of handling the parting between two coal seams. It consists of evaluations of parting stowing techniques applicable in a representative, thick seam western United States mine. Methods are examined for their potential implementation, and an estimated operating cost per yard of material moved is developed. The methods are of two categories castback or haulback. Haulback methods use truck haulage except With scrapers, and the castback methods are a direct stowage with no intermediate haulage equipment. Possible equipment combinations include draglines, shovels, hydraulic backhoes, bucket wheel excavators, scrapers, and front end loaders. The purpose of this report is to evaluate the effective competetiveness of the various alternatives.

Jan 1, 1975

By Robert H. Bedford

The Rogan-Mallery tin property is in the foothills on the south slope of the Tehachapi Mountains, Kern County, Calif. It was first visited by the senior author in August 1942, and exploration by means of trenching and diamond drilling began in May 1944 and was concluded in August of the same year. Cassiterite, associated with iron-rich gossan, occurs in a limestone roof pendant at places near or at its contact with the underlying granitic rocks. The cassiterite grain sizes range from 20 mesh to 150 mesh. Surface and diamond-drill samples showed tin ranging from traces up to 122.6 pounds per ton. Exploration by the Bureau of Mines included 2,100 cubic yards of trenching and the drilling of 11 diamond drill holes totaling 1,000 feet. Dana Hogan, president of the Rogan Petroleum Co. of Los Angeles, Calif.) brought these projects to the attention of the Bureau of Mines in July 1942, and the following month a Bureau engineer made a preliminary examination in company with Hillard Mallery, of 408 Ruby Street, Redondo Beach, Calif., the man who discovered them.

Jan 1, 1949

By E. Esponosa-Gomez, J. A. Finch, A. R. Laplante

"Water quality plays an important role in oxide flotation. The effects on selective flotation of fine (1-16 um) pyrochlore of two types of water used at the Niobec concentrator, potable and plant recycle, were assessed. Several pyrochlore collectors and silicate depressants were tested. Water effects were different for each mineral-reagents) combination. In general plant recycle water decreased selectivity and increased reagent consumption. Interpretation of results is given in terms of electrokinetic effects, hydrolysis of cations, and mineral-collector interactions. Two techniques of treatment for plant recycle water, cation precipitation and zeolite adsorption were assessed. The former was found to be more effective under the tested conditions but recycle water continued to give poorer selectivity than the potable.INTRODUCTIONWater quality plays an important role in selective flotation. Specific effects have been reported by many workers (1-6) and in general the better the water quality the more selective is flotation. Water composition depends on origin and the minerals being processed. For example pulp containing salt-type minerals (calcite, apatite, dolomite) will contain more Ca and Mg cations than that from a sulphide deposit. Another source of water contamination is the flotation reagents added to the pulp, particularly if water recycling is practiced."

Jan 1, 1986

The epizonal Ag-Pb-Zn vein deposit at San Bartolome is characterised by a base-metal sulphide assemblage containing the spectacular development of interpenetrating, bladed networks of pyrrhotite which have been replaced by marcasite and pyrite. A similar assemblage displaying the same crystal habits and textures are also a diagnostic feature of the Sn and SnAg deposits ofBolivia. On this basis, it is reasonable to conclude that both deposits were formed from fluids of similar nature and origin. Although no economic accumulation of Sn is known in San Bartolome, further comparison of the geologic setting, age, mineralogy, fluid inclusion data and magmatic association of this deposit with the Bolivian systems has highlighted additional similarities consistent with a hypothesis that more extensive Sn mineralisation might exist in the San Bartolome area.

Jan 1, 1995

By C. D. Thompson

Pile load test programs were carried out in 1984 and 1985 at Stelco's and Dofasco's Steel Making Plants in the Hamilton Bayfront area. 323.9 mm outside diameter by 9.5 mm wall thickness Grade 3 steel closed-end pipe piles were driven to practical refusal at depths of 21 to 30 m in very dense silt till with Delmag D30 open-end diesel hammers. Ultimate bearing capacities of up to 5330 kN were proved by dynamic monitoring and static load tests. Allowable bearing capacities of 1780 kN were achievable on production piles without undue difficulty. It was found that the impact stress at the top of the pile was controlled by the yield strength of the steel rather than a useable upper limit based on the modulus of elasticity. A bearing to impact stress ratio of 1.2 at practical refusal was observed to be reasonable but conservative at this site, and is felt to be generally applicable for piles driven to practical refusal elsewhere. Dynamic monitoring during production pile driving was able to show that apparent relaxation was caused by pre-ignition of the hammer when visual observations indicated that pile driving was proceeding satisfactorily.

Jan 1, 1987

By J. M. Font, R. G. Reddy

Jan 1, 2004