The contribution of heavy-duty haulage trucks to the concentrations of aerosols and criteria gases in underground mine air and the physical properties of those aerosols were assessed for three fuel blends made with fatty acid methyl esters biodiesel and petroleum-based ultra-low-sulfur diesel (ULSD). The contributions of blends with 20, 50, and 57% of biodiesel as well as neat ULSD were assessed using a 30-ton truck operated over a simulated production cycle in an isolated zone of an operating underground metal mine. When fueled with the B20 (blend of biodiesel with ULSD with 20% of biodiesel content), B50 (blend of biodiesel with ULSD with 50% of biodiesel content), and B57 (blend of biodiesel with ULSD with 57% of biodiesel content) blends in place of ULSD, the truck’s contribution to mass concentrations of elemental and total carbon was reduced by 20, 50, and 61%, respectively. Size distribution measurements showed that the aerosols produced by the engine fueled with these blends were characterized by smaller median electrical mobility diameter and lower peak concentrations than the aerosols produced by the same engine fueled with ULSD. The use of the blends resulted in number concentrations of aerosols that were 13–29% lower than those when ULSD was used. Depending on the content of biodiesel in the blends...
Purpose – The purpose of this paper is to compare the predictive capability of three methods of truck cycle time estimation in open-pit mining: computer simulation, artificial neural networks (NNs), and multiple regressions (MRs). The aim is to determine the best method. The most common method currently used is computer simulation. Design/methodology/approach – Truck cycle times at a large open pit mine are estimated using computer simulation, artificial NNs, and MRs. The estimated cycle times by each method are in turn compared to the actual cycle times recorded by a computerized mine monitoring system at the same mine. The errors associated with each method relative to the actual cycle times are documented and form the basis for comparing the three methods. Findings – The paper clearly indicates that computer simulation methods used in predicting truck cycle times in open-pit mining underestimate and overestimate the results for short and long hauls, respectively. It appears that both NN and regression models are superior in their predictive abilities compared to computer simulations. Research limitations/implications – The cycle time prediction models developed apply to a specific mine site and one has to be careful not to directly apply these models to other operations. Practical implications – The paper describes the implementation of regression and NN modelling. An opportunity exists for mines to utilise the large volumes of data generated to predict truck haulage cycle times more accurately and hence...
Fonte: The Australasian Institute of Mining and Metallurgy; AustraliaPublicador: The Australasian Institute of Mining and Metallurgy; Australia
Tipo: Conference paper
Publicado em //2012EN
Relevância na Pesquisa
It has long been recognised that narrow vein mining needs innovative approaches to mine access and mining methods in order to improve the economics of this vital part of the mining industry. The mining equipment used currently requires large openings in narrow vein-type deposits making mining operations uneconomical. In view of this and other shortcomings of the current mining practices, a study was initiated to investigate the potential of using low profile electric loader with mounted conveyor in conjunction with the electric monorail haulage system (EMTS) to load and haul the blasted material, particularly in decline development and main haulages. Computer simulation based on the General Purpose Simulation System/Henrikson (GPSS/H) is used to model the system and evaluate its performance. The results are compared with those for conventional mining using trucks and loaders. The EMTS provides competitive haulage rates in substantially smaller excavations than is currently achievable. According to simulation results, the electric loader in conjunction with the EMTS had the same number of blasts as the conventional system and hence the same advance rate of 3.33 m per 12 hour shift. Furthermore, the total drill-blast-load-haul cycle time was less than the conventional system by one hour.; http://www.ausimm.com.au/publications/epublication.aspx?ID=15191; B. Besa and E.K. Chanda
Landlocked Bhutan faces unique
challenges, and opportunities as it pursues the development
of its transport sector into the 21st century. Bhutan's
population growth rate is high, rural-urban migration is
accelerating, and, fueled by sustained economic growth, the
country is urbanizing rapidly, giving rise to an expanding
urban middle class, with rising expectations of well-paid
employment, accessible services, and consumption potential.
However, accessibility to a large measure depends on
availability of reliable, and affordable transportation.
Poor rural access is synonymous with rural isolation, and
poverty, while high external and domestic transport costs
constrain the country's economic and social
development. Transportation poses a considerable cost
disadvantage to business and commercial undertakings; road
transport is slow and regularly disrupted by landslides and
flooding; air transport is costly and erratic. Costly
transport is a major factor constraining the development of
tourism, horticultural exports...
In Lao People's Democratic Republic
(PDR), the value of trade has risen rapidly over the last
decade with both imports and exports increasing by average
annual rate of 24 percent. This report examines the trade
logistics of Lao PDR. A trade and transport facilitation
assessment was performed using a standardized toolkit and
methodology developed by the World Bank to evaluate the
quality of the logistics services. The assessment focused on
the services used by these trades and the corridors used by
these services. The assessment gave specific attention to
two constraints on trade, the location of the country and
the size of the trade. The study is organized in three
interrelated parts: assessing the performance of the
logistics sector; the international trade corridors linking
Lao PDR to trade gateways in Thailand; and the supply chains
used for distribution of exports. This report is presented
in four sections. The first part examines the foreign trade
of Lao PDR, the opportunities for growth and the logistics
services in the movement of imports and exports between the
country and its major gateways. The second section evaluates
the performance of the corridors connecting the major
origins and destinations in the country and the principal
seaport used for international trade. The third section
analyses the structure and performance characteristics of
the supply chains used for selected trades and the
implications for restructuring to support growth in the
export trade. The final section presents a series of
recommendations for improving the competitiveness of the
exports through improvements in the structure of the supply
The goals of minimizing emissions and lowering operating costs by monitoring and controlling fuel efficiency have been a growing concern in the mining and construction industries. The largest single contributor of energy consumption in an open pit mining operation is haul trucks. At Goldstrike Mine, haul trucks accounted for approximately 67% of fuel used in 2010. By examining haul trucks in their operating environment, strategic changes in critical parts of the truck cycles can result in fuel savings. This project was a subproject of the Mine Traffic Optimization (MTO) project and is funded by MITACS and Barrick Gold Corporation. One objective of the MTO project was to examine how mine traffic affects fuel efficiency.
Certain components of the haulage profile result in inefficient use of fuel, which results in increased operating costs and a larger environmental footprint. Monitoring the trucks in real time allows for the examination of various ways to modify truck’s behaviours in order to improve fuel efficiency. One critical component of the haulage cycle is intersections. An analysis was performed to gain a better understanding of efficient intersection layouts and travel speeds. Cycle time analysis was conducted to ensure that alterations to the haulage cycle would result in minimal impact to the overall productivity of the mine. Modifications to operating practices and simple coding changes to the dispatching program suggest possibilities for potential fuel savings...
As open pit mines get larger and their road networks more complex, haul road traffic is an area of increasing concern for mine operators. In particular, engineers from Barrick Gold Inc. have observed haul truck interactions in some of their larger open pit mines that are clearly disruptive to the haulage cycle. Such traffic effects cause uncertainty in haul times over identical routes and commercial dispatch systems do not explicitly account for this variability. This research, based on first-hand data collected from the Goldstrike Open Pit in Northern Nevada, focuses on assessing the level of variability in haul times, identifying the sources of said variability, and determining the effects on haulage optimization. Initial data analysis shows different levels of variability over the range of observed haul times, and further investigation identifies certain haulage parameters as significant sources of said variability, such as road topography and intersection effects. Focusing on these areas of interest, relevant data sets were manipulated to reduce levels of data dispersion and compared to observed results in order to quantify the effects in terms of changes to overall mean haul times along identical routes. It was observed that variability has a negative impact on travel times and moderate variability reduction was observed to increase productivity by 1–2 % when used as an input to a simple dispatch simulation program based on the Goldstrike Open Pit.; Thesis (Master...
This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.trd.2015.09.010; Reducing the empty weight of articulated heavy goods vehicle trailers is one avenue that needs to be explored in reducing the carbon footprint of the road freight industry as a whole. A statistical analysis of two heavy goods vehicle fleets operating in the United Kingdom has helped to identify double-deck trailers used in grocery haulage and 'walking-floor' trailers used in bulk haulage as two examples of trailers that can benefit significantly from lightweighting. Energy consumption of numerous articulated heavy goods vehicles is quantified through an idealised drive cycle analysis reflecting a long haul journey over a highway. This energy analysis allows for a mass energy performance index to be established. The analysis has shown that reducing the empty weight of trailers by 30% can cause reductions of up to 18% and 11% in mass energy performance index for double-deck trailers and 'walking-floor' trailers respectively. Using this approach, trailers that will benefit the most from weight reduction can be identified systematically, allowing for lightweighting strategies to be implemented more effectively. Strategies to reduce empty trailer weight and improve vehicle utilisation are also discussed; The authors would like to acknowledge the financial support from the members of the Centre for Sustainable Road Freight and from the Engineering and Physical Sciences Research Council (Grant Reference EP/K00915X/1).