12E-08_trykk.pdf

PREFACE

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ROCK QUARRYING - Transport REPORT 12E-08

The report is one of five reports concerning rock quarrying: 12A-08 ROCK QUARRYING Quarry Design 12B-08 ROCK QUARRYING Blast Design 12C-08 ROCK QUARRYING Bench Drilling 12D-08 ROCK QUARRYING Loading 12E-08 ROCK QUARRYING Transport A considerable amount of information on surface blasting and earth moving has been brought up to date and systematized through these reports, to be used for:

Placement and design of rock quarrying Blast design Estimation of production capacities and costs Cost analysis, tender, budgeting and cost control Choice of method and equipment

The present report is mainly a tool for production planning, choice of equipment and prediction of time consumption and costs in rock quarry transport. The report is also used as a textbook and contains detailed parts concerning transport mechanics. The report contains experience data concerning capacities and costs from field research since the 1970s. The transport mechanics and its estimations are closely related to models described in actual literature. The report is prepared by Vegard Olsen as a part of his PhD thesis entitled Rock Quarrying Prediction Models and Blasting Safety and it contains updated capacities and prices for new technology and equipment Economic support for field data collection has been provided by partners presented in Appendix A.

PREFACE

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For reference, registration and similar, we ask for the following: NTNU Department of Civil and Transport Engineering (2008): Report 12E-08 ROCK QUARRYING Transport. Trondheim, December 2008 Amund Bruland Professor

1. INTRODUCTION

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General

The report is meant to be a tool for transport of rock in quarries and surface mines. Transport fleet planning, choice of equipment and estimation of transport capacity and costs, is the issue of the report. Combined with the other reports in the Rock Quarrying series, a toolbox for improvements and optimization of the total quarry production line is available. Combined with report 12D-08 ROCK QUARRYING Loading, this report represents a complete model for earth moving projects. The reports prediction model treats construction and mining trucks operating with payloads larger than 25 tons. This includes articulated dump trucks and rigid chassis dump trucks. A comparison with load and haul by wheel loaders is made. Transport by highway trucks and semi trailers is treated extensively in [3] and [6]. A general overview of most transport vehicles and systems are mentioned. Transport mechanics, concerning: Travelling resistance, traction and brake power and road conditions are treated extensively in the report. This gives knowledge about the basics of the transport capacity and cost estimations, as well as an expanded understanding of the quarry design principles described in report 12A-ROCK QUARRYING Quarry Design. The price level of this report is December 2008. Adjustment of prices can be done by using the Construction Machinery Index which is updated every month by the Department of Civil and Transport Engineering at NTNU. Subscription can be arranged by contacting [email protected]. Products

There are many manufacturers of dump trucks in the market. The manufacturers will continuously be developing their products and new names and models will occur. The report database embraces most manufacturers in the Norwegian market. There are made no difference between equipment with equal performance specifications. The data resembles equipment currently used in the industry (2005-2007).

2. TRANSPORT EQUIPMENT 2.1 Transport methods

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2.1 TRANSPORT METHODS

2.11 General

Mass transport in relation to quarries takes place with different kinds of means of transport vehicles and systems:

Dump trucks Articulated trucks Commercial trucks and semi trailers Load and haul Tractor scrapers Track-bound wagons Bulldozers Conveyor belts

The trucks in the two first bullet points will be extensively treated in the report. Load and haul will be treated as a special case. The other will be described shortly in the following sections.

2.12 Commercial Trucks and Semi Trailers

Commercial trucks and semi trailers have a low axel weight and can be used on public roads. Lately, the payload capacity and engine power for these vehicles have increased to the point where they in special cases can compete with the smallest dump trucks off-highway also. The payload range is from 15 to 50 t. Highway trucks and semi trailers are extensively treated in [2] and [6]. The advantages of the commercial trucks compared to dump trucks are:

Versatility - applicable on public roads Low deadweight - high relative payload - good CO2 accounts Narrow chassis - avoid meeting stops - reduced road and tunnel costs Low purchase price - high second hand value

The disadvantages in construction work are:

High repair and maintenance costs - limited economic life Vulnerable to road surface - low tyre life Low flywheel power - limited road grading Low maximum payload - limited maximum capacity


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2.13 Scrapers

A wheel tractor-scraper is a self-loading hauling system without the need for any auxiliary machine in either end of the process. It is mainly used for moving of homogeneous masses lying in an even plane, mostly sand, soils and clays. The largest machines can do board materials and can be used in general construction, heavy construction, mining and waste. The front (tractor) looks like the front of an articulated dump truck. The rear part has a vertically moveable bowl with a sharp horizontal front edge. The bowl can be lowered and raised. When the front edge is lowered, it cuts into the ground like a cheese slicer and fills the bowl. The maximum cut depth is about 40 cm for the largest machines. When loaded the blade is raised, and the bowl closed. The wheel scraper transports its load to the fill area. The back panel of the bowl is opened and the load tumbles out. Maximum spread height is up to 70 cm, depending upon size of the machine. Scrapers can be very efficient on short hauls where the cut and fill areas are close together and have sufficient length to fill the bowl. The payload range is from 15 tons to 50 tons.

Figure 2.1 Wheel tractor scarper (35 t)


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2.14 Bulldozers

Moving of masses by bulldozers is only applicable over short distances, no more than 200 m. The dozers are normally used in construction work and landfill operations. The working principle is to push the material in front of the blade. The capacity varies by the size of the machine, size of the blade and the material. The largest dozers can push up to 70 tons of material. In construction of rock fill dams and rubble mound structures, the dozers normally place and level the quarry run at its final destination, after it has been dumped by trucks. The dozers may also be used in loading operation from stockpiles. Figure 2.2 shows the machine used to load coal from a stockpile into a crusher.

Figure 2.2 Dozer (105 t) used to push coal into the crusher. Mass moving capacity 60-70 t.


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2.15 Rail Cars

In open cast works, hauling by rail cars is mostly applicable when the large quantity of masses must be transported over long distances. Typical applications in open cast works are:

Hauling of waste when deposits close to the open-cast is getting full. Hauling of raw material between the quarry and the processing plant Hauling of raw material from distant excavation locations

In tunnelling and underground mines, rail transport is advantageous due to the working environment (i.e. air pollutions) and the reduced haul tunnels. Earlier (more than 50 years ago), rail transport within the opencast was more common, with direct loading into the rail cars. This rarely happens today due to high productivity and relative fast moving of the loading points, hence the costs for building the rails becomes too big. Today the loading happens beside the pit from stockpiles (wheel loader) or directly from silos (fine material).

2.16 Conveyor Belts

Conveyor belts are mainly used to transport crushed material from a quarry or mine to a nearby stocking area or a harbour. Conveyors belts require large investments, however the running costs are low and they can compete with trucks under special conditions. Combined with silos, conveyors can work all day around, which is advantageous e.g. in loading ships to keep the loading time as low as possible. In some large distant mines, conveyors are conducted all the way into the loading area. The end conveyors are transportable and may be moved during blasting and as the loading point changes. Due to limitations of the fragment sizes loadable on the conveyor a transportable crusher is needed in this system. Many types of conveyor solutions are available, however not mentioned further here.

2. TRANSPORT EQUIPMENT 2.2 Construction and Mining Trucks

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2.2 CONSTRUCTION AND MINING TRUCKS

2.21 Rigid Dump Trucks

The rigid dump trucks are used where major transport of rock masses takes place. The trucks are front wheel drive with a medium to very large payload capacity (40 to 300 t). Mass transport usually demands a road system of its own. Rigid dump trucks are by far the leading transport vehicle used in quarries today. Most of the trucks used in Norway are so called diesel-mechanics. The power is supplied by a diesel engine which transfers the power to the wheels via a gear box. Usually a converter is mounted between the engine and gear box. This will attain smoother shifting and reduced mechanical wear.

Figure 2.3 Rigid dump truck (90 t) loaded by wheel loader (73 t).

The challenge for the largest trucks has been to obtain a satisfactory transfer of power to the wheels and an adequate braking capacity. With this in mind, diesel-electrical trucks have been developed. They operate as follows:

A diesel engine drives an AC generator giving power to a DC motor mounted in each of the wheels. All transmissions are electrical and operate without moving parts.


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The electrical engine functions as a generator when it comes to braking. The electricity produced leads to an adjustable resistance which causes the actual braking force. The diesel-electric system has several advantages:

The engine operates with constant revolution, reducing the engine wear. Due to constant revolution of the engine, the hydraulic system always operates at

full capacity. No mechanical transmission to the wheels. Reduced mechanical wear and

increased lifetime for the machine. The machine is equipped with an anti-spinning mechanism. This gives reduced

wear of tyres. Nevertheless, diesel-electric trucks have not gained a large market in Norway. This is mainly due to their complexity, which requires higher competence both for service and operation, compared to the mechanical trucks. Due to this, the second hand value (sale-value) is lower compared to the diesel-mechanical trucks. Diesel-electric trucks will not be covered in detail in this report. The sizes of rigid dump trucks span from 40 to 300 tons payload, however the diesel-electrical trucks are only applicable from approx. 90 tons and up.

2.22 Articulated Dump Trucks

The articulated dump trucks are often used in construction projects where the access or transport roads may not be optimal at all times. The articulated trucks are cross-country transport vehicles with a small to medium payload capacity (20 to 45 tons). In quarries they are often used to transport waste rock to a deposit where both the loading area and the tipping area may have unprepared ground conditions. The articulated trucks have permanent 6-wheel drive, which is a significant advantage in rugged terrain. The 6 wheel-drive makes the vehicle applicable in soft and slippery ground conditions. Independent front suspension ensures good ground contact and stability. The rear boogie may have rigid or oscillating boogie. The latter gives ground contact on all wheels at any time. All wheel ground contact ensures equal weight distribution and less wear on bearing parts. It is essential in rough terrain.


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Figure 2.4 Articulated, six-wheel drive dump truck (37 t).

Good manoeuvrability due to oscillation in the boogie..

2. TRANSPORT EQUIPMENT 2.3 Load and Haul

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2.3 LOAD AND HAUL

Load and haul by wheel loaders are applicable in situations where the distance from the rock pile to the crusher or a shaft is very short (less than approx. 100 m). In small quarries with low annual production, the cost optimal length may be increased a bit due to increased investment and labour costs when using an extra machine. In block stone production the wheel loader is applicable for sorting and transporting the largest blocks (larger than 3.0 t) between the blasted rock pile, stock piles and the final construction. The wheel loader handles the blocks more gently than dumping from trucks.

Figure 2.5 Load and haul of block stone (~8 t) by wheel loader (126 t).

Rock Quarrying - TransportPreface1. Introduction2. Transport equipment2.1 Transport methods2.11 General2.12 Commercial trucks and semi trailers2.13 Scrapers2.14 Bulldozers2.15 Rail Cars2.16 Conveyor belts

2.2 Contruction and mining trucks2.21 Rigid dump trucks2.22 articulated dump trucks

2.3 Load and haul

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