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By G. R. Adhikari

Step 4: Selection of explosives and initiation system Various types of explosives are manufactured in India and a wide choice is available among them that include nitroglycerin based explosives, slurries, emulsions, ANFO (ammonium nitrate mixed with fuel oil) and heavy ANFO. The choice is also available between cartridged and bulk loading systems. In Indian mines, much importance is unduly given to the cost of explosives alone which is not conducive to optimization of blast design parameters. The concept of energy per meter of blasthole and the way in which the total explosive energy is partitioned between shock and heave is not considered in the prevailing practices. Besides, very little efforts are made to objectively evaluate the performance of explosives for a given site condition. Tailoring explosives is limited to changing the density of the bulk explosives. Cartridged explosives are still being extensively used in large operations where bulk explosives should be the preferred choice.

Jan 1, 2002

By Y. Wang, K. S. E. Forssberg, A. Johansson, X. Lu

This paper presents the desulphurisation of a fine graphite powder below 80 µm by high gradient magnetic separation. The removal of pyrite (FeS2) and pyrrhotite (Fe1-xS) from the fine graphite powder was carried out with a modified version of the Sala dry HGMS with vibration assistance. In addition, a comparative study with dry and wet HGMS systems has also been performed. In order to establish the performance of the desulphurisation, a test series of varying parameters such as magnetic induction, matrix type/configuration and vibration were performed. As an equipment/process for removing sulphurous impurities from the fine graphite powder, the dry HGMS is deemed useful and comparative with the wet HGMS.

Jan 1, 2002

By Q. Lui, J. Oxenford

The occurrence of heavy minerals in the oil sands of Alberta has long been known and has been well documented in the literature. Unfortunately most of the researchers working on this resource have been unable to produce products that meet acceptable market specifications. This has resulted in many misconceptions about this resource. Recent efforts have shown that with some innovative approaches, marketable material can be produced and as a result it might finally be possible to realize the potential of this immense resource that, some have estimated, could contain in excess of 20% of the world demand by 2010. This paper highlights the uniqueness of this mineral assemblage and the mineral processing challenges it presents. It shows the most recent work that has resulted in the production of marketable titanium and zircon products. This paper also focuses on some of the special problems resulting from the variability in the heavy mineral suite. Of special interest is the occurrence and removal of bitumen and pyrite without adding to the sulphur dioxide loading in the regional airshed. The trend by the mining industry to develop various positions on ‘sustainable mining’ has some significance for the heavy mineral industry. Although the industry generally has an excellent track record of eventually rehabilitating disturbed ground in an acceptable manner, heavy mineral mining operations tend to have a relatively large footprint of disturbance and the industry is under considerable pressure to develop options that are more environmentally acceptable. In addition, as operators move to exploit deposits that are lower grade and/or are further from a port site, the emissions per unit of sold product will also rise and the industry will be under pressure to address this issue as well. Because heavy minerals from oil sands are by-products of existing operations, there are virtually no incremental disturbances or emissions that would be associated with heavy mineral production. All mining and tailings remediation issues are accounted for by the oil sand operation. The only incremental emissions would be those associated with the mineral processing operations and transport of finished products to a port site. This paper discusses the environmental and cost implications of this situation.

Jan 1, 2003

By Xu Ronglie

This paper looks back on the developments and achievements of deep foundations, on the basis of the complex geological conditions and environments in China. It sums up advances in theoretical and applied researches, engineering constructions, practical experiences, case histories, and problems and developing prospects of piles and deep foundations in recent years in China.

Jan 1, 1991

By G Wyartt

Systems such as Davey Bickford’s Daveytronic® SP blast initiation system and electronic detonators have been an integral part of drill and blast activities in Australia for over a decade, with the significant benefits of electronic blasting well documented. Since 2010 the Multiblast feature has been commercially available, which enables eight individual blast patterns (up to 1500 detonators each) to be blasted in the same firing window. Synchroblast has been in active operation since 2012, which allows a blast of up to 4500 detonators – either as a single blast pattern, or several smaller adjacent blast patterns – to be reliably initiated.Multiblast manages blasts separately but concurrently, allowing all blasts to conduct prefiring checks simultaneously from the firing point utilising only one remote blasting unit. Each blast can be selected and fired individually, in a sequence determined by the operator by scrolling through the colour display. Synchroblast automatically detects the blasting configuration, and manages all detonators as a single blast pattern. This simplifies the design and blasting processes for the mining operation.Multiblast and Synchroblast are routinely employed throughout Australia and globally in both open cut and underground operations, enabling optimal productivity due to increased blast volume and reduced operational downtime associated with blasting events.A number of case studies will be presented in this paper, detailing various mining operations that are consistently blasting in excess of 2500 detonators per blasting event as a part of standard drill and blast operations. Blasts over 3000 detonators are becoming more frequent as mine planning departments adapt to this operational capability and flexibility.CITATION:Wyartt, G, 2017. Multi and Synchroblasting – maximising operational productivity, in Proceedings Iron Ore 2017, pp 631–634 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Daniel L. Hanson

This paper presents a case history of the design, installation and performance of a tied-back tangent caisson retaining wall which was constructed as part of the Third Harbor Tunnel project currently underway in Boston, Massachusetts. The Third Harbor Tunnel project consists of a large multi-lane transportation tunnel which is being constructed by the sunken tube method. In this type of construction, the tunnel alignment, slopes and bedding are excavated and installed underwater and the tunnel sections floated over the proper alignment and sunk in place. The tangent caisson retaining wall discussed in this paper was constructed to provide support of the upper portions of the tunnel excavation at the East Boston Portal where the tunnel exited from below the harbor and continued underground on shore. A portion of the tangent caisson retaining wall was also utilized to provide earth support for the barge unloading facility where spoil from the tunnel excavation was transferred to surface vehicles for removal from the site. PROJECT BACKGROUND The tangent caisson retaining wall was constructed by The Millgard Corporation (TMC) as a subcontractor to the Boston Third Harbor Tunnel Contractors, a Joint Venture which consisted of the firms of Morrison-Knudsen Corporation, Interbeton Inc., and J.F. White Contracting Company. The entire project team is listed below on Table 1. The design of the tangent caisson wall system was performed by Hanson Engineering, P.C. (HE) acting as design consultant to TMC. The retaining wall system incorporated a single row of pressure injected earth anchors (tie-backs) as part of the design. The earth anchors were designed and installed by Drill Tech as a subcontractor to TMC.

Jan 1, 1994

By R. F. Chaiken

The Bureau of Mines has carried out experimental and theoretical studies with prilled and pulverized ammonium nitrate-fuel oil (AN-FO) mixtures containing varying amounts of fuel oil in an attempt to quantify the effects of stoichiometric composition, nonideal detonation behavior, and expansion volume on the production of CO, NO, and N02 fumes. Experimental fume measurements were obtained in the Bureau's large closed gallery facility (7.2 X 104 liter expansion chamber) and in the standard Crawshaw-Jones apparatus (90--liter expansion shamber) using a prepackaged charge configuration containing about 450 g of explosive.4 The theoretical calculation of toxic fumes was achieved with an equilibrium detonation code called "TIGER,," Contrary to initial expectations, the NOx (= NO + N02) fumes from the large gallery test were found to be in essential agreement with the Crawshaw-Jones results. It was also concluded that (1) "TIGER" calculations offer a good approach to the prediction of toxic fumes; (2) there is a basic problem in extrapolating laboratory measurements of CO fumes to mine conditions--this being due to postdetonation oxidation of CO to CO2; and (3) the detonation velocity decay rate of an explosive is a useful experimental parameter for correlating toxic fumes production with nonideal detonation behavior.

Jan 1, 1974

By D. He

In China, the total reserves of vanadium, reported as V2O5, in stone coal is 118 Mt (130 million st). Recovering vanadium from such a large resource is very important to China?s vanadium industry. The technology now being used to recover vanadium from stone coal has the following two problems in the leaching process: a low recovery of vanadium and high acid consumption. To resolve these problems, a new leaching technology is proposed. The effects of factors such as H2SO4 concentration, liquid-solid ratio, temperature and time, and the types and additions of additives were studied. By adding 1.5% (by weight) CaF2 and leaching the roasted residue of stone coal with 5.4% (by weight) sulfuric acid at 90°C for 12 hours at a liquid-solid ratio of 2 mL/g, the leaching degree of vanadium reached 83.10%. This proposed leaching technology gives a feasible alternative for the processing of roasting residue of stone coal and can be applied in the comprehensive utilization of stone coal ores in China.

Jan 1, 2008

By John E. Newby

The Brightwater Conveyance System consists of four tunnel segments in three tunnel con-tracts, comprising over 21,760 m (71,400 ft) of pressurized face tunneling in complex glacial and non-glacial soft ground conditions with a large proportion 60 m (197 ft) or more below the ground surface with up to 7 bars groundwater head. This resulted in unique technical challenges for establishing geotechnical baseline values. The process used to develop these baseline values and specifications with regard to the level of risk that the owner, King County, was willing to accept is described in this paper.

Jan 1, 2008

By A. M. Clegg

In general, overall experience has shown that the approach to the appointment of a project manager is given much attention, but little specific attention is given first to the risk associated with the project conceptual design and its overall executability within either the new legislative framework or the sustainability of the outcome. The risk in project executability and sustainability within the ?new age? legislative framework of the Mining Charter, etc, is itself however, of far greater importance. The degree of importance being defined by the intended projects impact on the business going forward. This is particularly the case where the intention of the implementation is effectively to turn around or even enhance a loss-making strategic investment like a mine or process plant operation in an ?old-order rights? or Brownfield?s operation. This paper attempts to highlight the importance of a ?pre-project project? (PPP) to mitigate the risk in the ?new age?, with specific reference to operational due diligence (ODD) and project conceptual design.

Jan 1, 2005

By S. L. Gerhard

In the United States the performance characteristics of permissible explosives are controlled by routine tests, which include firing the explosive into a gallery filled with a methane-air mixture. These tests are made by the staff of the Explosives Division of the Bureau of Mines and, are similar, in general, to those employed in other countries. This control has helped to reduce the frequency of accidents involving the ignition of firedamp by explosives but has not clarified the basic causes, of the ignition. To advance this control and to minimize potential hazards further, this fundamental knowledge is needed. Some of the results of recent research on the causes of the ignition are described herein. NATURE OF THE PROBLEM When an explosive ignites firedamp in the gallery tests, the source of the ignition must be one or more of the emissions from the steel borehole. It has been accepted generally that these emissions are (1) particles, (2) the shock wave, and (3) hot gases and flames. Photographs show that the shock wave emerges from the borehole first, followed closely by hot gases. At first the velocities of these are high and approximately equal, but the velocity of the gases decreases more' rapidly than that of the shock wave, and by the time the reactions causing the flame are complete the shock wave travels in an otherwise undisturbed medium. The particles are originally enveloped in the hot gases but some soon begin to break through and eventually out-distance the shock wave. The approximate geometry of these emissions about I millisecond after the shpt is fired is illustrated in figure

Jan 1, 1939

By A. Aitio

Sustainable development is one of the central themes of the work of the World Health Organization; chemical safety is one of its important components. For more than 25 years, WHO has had specialized units for assisting member countries in dealing with their problems in chemical safety. For one of the units involved, International Programme on Chemical Safety, a reorientation is in progress to make best use of existing resources, and to prioritise the work to optimally correspond to the needs of the member countries. The risk assessment work of IPCS, and specifically, the work on chromium and chromium compounds, are discussed.

Jan 1, 2004

A clay binding agent has been investigated to enhance flotation recovery of bitumen from Canadian high fines oil sand in the Clark Hot Water Extraction (CHWE) process. Selective adsorption on fine particles and subsequent agglomeration are critical for the success of clay binder enhanced oil sand flotation. A number of flotation tests have been performed at different reagent dosages under different operating conditions such as pulp pH to evaluate the reagent performance. Dissipative Quartz Crystal Microbalance (QCM-D) analyses of clay binder adsorption on quartz were carried out to better understand process mechanisms. It has been found that use of clay binder in flotation resulted in an absolute bitumen recovery increase of 18%, 25%, and 11% for the high-, medium-, and low-grade oil sand samples, respectively. The QCM-D analyses have revealed that the clay binder was strongly adsorbed on the SiO2 surface.

Jan 1, 2012

By J. L. Hoover

The goal of the drill bit consumption study was to develop an equation(s) based on various components that affect bit drill wear and use the equation(s) to estimate the consumption of bits during production drilling. Drill bit data from various geographic locations were compiled and used to develop linear regression equations using the Microsoft Excel Software. Multiple drill bit consumption equations were developed and statistical analysis was used to verify the accuracy of those equations. The equations will allow mining companies to more accurately forecast drill bit consumption when evaluating new mine properties. This capability becomes increasingly beneficial to forecasting as the cost of consumables increases.

Jan 1, 2012

A Novel Diagnosis and Evaluation Procedure for Flotation Plants

Sep 13, 2010

By Mark X. Haley

Foundation design and construction in Boston has changed dramatically during the past 10 years. Prior to 1985, the primary foundation element in Boston, where deep foundations are required, was driven end-bearing piles. Since 1985, drilled or excavated high capacity foundation elements have been utilized more frequently. This paper will provide a historic perspective of their use and a summary of design parameters for elements installed and founded in the bedrock. TOPOGRAPHY Boston was founded in 1630 by the Massachusetts Bay Company of John Winthrop and his hearty band of Puritans. The settlement was chosen for: ? its safe harbor, ? abundant source of fresh water, and ? peninsula setting offering protection of the ocean on almost all sides with high ground for fortification. These three factors were a direct result of past geologic processes that created the Boston Basin by erosion of the soft bedrock underlying this area as compared to the harder granite rock to the north, west and south. As the glacial ice sheets melted and moved northward, various soil types were deposited. During ice sheet re-advancement the hills and islands of Boston took on their precolonial shapes. The Trimont, consisting of Beacon, Mt. Vernon and Pemberton Hill, rose to 150 ft above sea level with the smaller Copps and Fort Hill to the north and south.

Jan 1, 1994

By Jacques Deraisme

The technology of percussion drilling is well mastered. The lower cost of percussion drilling allows more holes to be drilled for the same budget. However significant differences are often observed between percussion and diamond drill assay data. This is due to the increased level of contamination associated with the percussion drilling process. Statistical studies on twinned drillholes show that diamond and percussion assays cannot simply be merged in a traditional kriging approach. The question then arises on how to use both types of data to produce reliable resource estimates. To take into account the lower reliability of the percussion assays, a noise characterized by a variance is added to these data. The methodology consists of two steps: 1. Cokriging of the equivalent diamond value at the percussion assay locations. 2. Block kriging using diamond assays and equivalent diamond values, calculated previously, adding to these data a noise, whose variance is the cokriging variance of step 1. This particular way of achieving kriging is called kriging with variance of measurement error. The paper illustrates this innovative methodology with an application on an iron deposit. The results of this method is compared to block kriging using only diamond assays and the gain in precision is quantified. An extension of that approach to multi-element cokriging is also presented.

Oct 1, 2009

Council for 1999/2000 President M.H. Rogers President Elect Dr L.A. Cramer Vice Presidents Senior A.A.B. Douglas Junior S.J. Ramokgopa Immediate Past President J.R. Dixon Honorary Treasurer J.A. Cruise [ ] Annual report In accordance with the current management policy, this report on the activities of the Institute is presented under eight main headings: 1. Interests of Individual Members 2. Technical Meetings 3. Publications 4. Regional Development 5. Engineering Science and Technology in South Africa 6. International Liaison 7. State Liaison 8. Management and Administration.

Jan 1, 2001

By R. A. Franks, G. F. Friel, J. C. Edwards, L. Yuan

The reversal of smoke products-of-combustion (POC) from a mine fire was determined in a mine section with the airway connectivity of an electrical Wheatstone bridge. Four diesel-fuel fire experiments with fire heat-release rates between 504 and 771 kW were conducted in the Safety Research Coal Mine (SRCM) located at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Research Laboratory (PRL). Smoke reversal propagated upwind from the fire with significant leakage into the upwind diagonal airway and without causing a complete reversal of airflow in the diagonal airway. A control measure consisting of a brattice suspended half entry height from the entry roof was determined to abate the smoke rollback. Computational fluid dynamics (CFD) analysis of the smoke movement agreed with the measurements.

By Yijun Caoa, Xiuxiang Taoc, Zhongbo Hub, Yinfei Liaoa

A new preparation scheme for a difficult-to-float coking coal from the Kailuan Mine, Tangshan, China was investigated. The results showed that grinding followed by column flotation was beneficial for obtaining products with low ash content. The positive effect of grinding on the coal floatability is attributed to the liberation of intergrowths and coal surface improvement. Tests indicated that 10 minutes was the optimum grinding time, and over grinding resulted in a deterioration in flotation performance. With a grinding time of 10 minutes, conventional flotation had potential to yield a product with around 12.42% ash content and 69.15% combustible recovery. Column flotation can reduce the product ash content to 11.15%and increase combustible recovery to 74.47%. Consistently better flotation results reveal that column flotation is more efficient than conventional flotation for such fines.

Jan 1, 2015