MODERN INFRASTRUCTURE IN COAL INDUSTRY
with reference to
MOZAMBIQUE COAL
Lyonell Fliss Pr Eng (Civil)
Lyonell Fliss & Associates (LFA)
Industrial Civil Engineering Consultants
Coal Mining Developments include in general large Material Handling and Storage
facilities and the Civil Engineering Infrastructure for Coal Mining has its specific
aspects compared with other sectors of the mining industry.
As coal is an important commodity for local usage but mainly for export, the new
developing Mozambique coal industry which combines mining, land transportation
and coastal export terminals, considering its potential large scale operation, will
require amongst other engineering features a modern infrastructure to sustain this
industrial enterprise.
Specific of Mozambique conditions for its coal mining industry are the location of
the coal deposits (e.g. Moatize coal fields in Tete province basin ) relatively isolated
from industrial developments and large distances to multiple potential coastal
exporting ports (Beira , Nacala, Matola).
In addition to the location conditions, the coal mining in Mozambique is affected by
the tropical climate, particularly aggressive at the coast due to marine environmental
factors.
To overcome these specific adverse conditions, it is necessary, regarding at least
the infrastructure, that the engineering should address problems of high durability,
easy constructability and minimum maintenance, within the cost and time available
for the whole development.
The paper presents new innovative concepts characteristic to the coal mining
industry for infrastructural main elements, with working solutions in the form of
already built structures in operation and other under construction or R&D prototypes,
as examples.
In our opinion the proposed concepts are applicable in the case of Mozambique coal
mining industry and their advantages in the specific conditions of Mozambique are
multiple and described below.
The characteristic infrastructural elements for the coal mining industry we refer to
are:



Bunkers of large storage capacities , of 10-40 000T and more
Overland coal conveyors of various configurations, lifts and lengths up to
30km and possibly more without transfer points
Coal Stockyards equipped with stacker/reclaimers or overhead conveyors
with reclaim tunnels and conveyors.
Innovative Concepts for Infrastructure in Coal Mining Industry
For all above referred structures, particularly in the Mozambique environmental
conditions, we consider that precast, high performance concrete should be
considered the preferred construction material compared to the conventional cast
in-situ concrete or structural steel and its use for these applications should be
maximized.
Coal Bunkers
Conventionally these structures are of in-situ concrete construction and whilst for
small capacities (up to 5000T) this system may be adequate, for larger capacities it
becomes uneconomical and difficult to construct.
The alternative is precast concrete construction which not only overcomes the above
mentioned problems , but in addition provides superior quality through high strength
concrete (60MPa), increased durability (to abrasion in particular), improved coal
discharge through smooth sliding surface finish that makes redundant internal lining
, an expensive and difficult item to install and maintain (Fig.1).
A number of precast coal bunkers, operating or under construction confirmed the
above described advantages of precast construction versus in-situ. It was also
proved that these advantages increase with the increased size of the bunker as it is
the general case with any precast structure.
Coal bunkers may be used as mining production buffers or as live coal containers for
multiple wagons rapid loading-out stations.
Overland Coal Conveyors
Modern coal transportation from mine to load out stations or power plants is carried
out by overland conveyors for distances up to 30km and even more, following a 3D
curved geometric route, without any intermediate transfer points.
Long overland conveyors can be used to create reticulations covering large coal
fields, concentrating the various mines product to a point where it can be rapidly
loaded in trains connecting directly to the export ports.
This conveyor mechanical technology needs to be supported by a structural
framework. Conventionally this structure consists of steel frames at 3-5m centres
supporting the idlers, belts, coal and cladding and are founded on concrete gravity
sleepers (sleepers providing structural stability through own weight).
Two new alternatives are available for the overland conveyor supporting structures,
1. Replacement of heavy gravity sleepers by light precast sleepers on minipiles
which instead of providing stability through weight are using soil resistance
instead. (Fig. 2)
This system was proved economical, reliable and fast to install in a number of
coal projects during the last years.
2. Replacement of conveyor steel frames with precast, ultra high strength
(100MPa) concrete, also on minipiles without sleepers as the concrete frame
itself is stiff enough (Fig 3 and 4).
This concept was tested on full scale prototypes and proved to be reliable
regarding integrity, strength and durability , in addition of being faster to install
and more economical than conventional.
Coal Stockyards
Stacker / reclaimer equipment requires conveyor supports at close cents for long
distanced and for this application precast concrete supports could be an
advantageous alternative under the Mozambique specific conditions,
Conclusions
With its extraordinary large reserves of high quality export coal, Mozambique may
face difficult logistic problems by having coal fields dispersed on a large area on one
hand and multiple potential export ports on the other (Fig 5).
To connect individual mines by rail directly to each of the ports it may create traffic
difficulties which would result in delays , slow loading ,wagon underutilisation, with
final result of high costs of in-land transportation (Fig 6) .
To overcome this situation, our recommendation is to create at least one in-land coal
terminal, where the coal can be collected from various mines by a reticulation of long
overland conveyors, stockpiled, and rapidly loaded from bunkers in the trains aiming
to various ports.(Fig 7 and 8)
The overall coal logistic system for the Mozambique Coal mining industry , as this
industry is at present only at its beginnings , should be based on an Master Plan to
be developed with the participation of all the major players , resulting in an
optimised and flexible system, by making allowance (at least for space) for predicted
future developments.
The modern infrastructural components, such as large capacity bunkers, long
overland conveyors and large stockyards are already available and tested, making
implementation of a modern coal industry infrastructure in Mozambique a real
possibility,
.
FIG 1: PRECAST BUNKER
FIG 2
FIG 3: MINIPILE SUPPORT
FIG 4
FIG 5
FIG 6
FIG 7
FIG 8
Paper Title:
MODERN INFRASTRUCTURE FOR COAL INDUSTRY
with reference to MOZAMBIQUE COAL
Author’s Details:
Name: Lyonell Fliss Pr Eng (Civil)
Organization: Lyonell Fliss & Associates, Industrial Civil Engineering Consultants
POB 3929 Edenvale 1610. Gauteng
Tel. 011 454 2747
Cell 083 632 3799
e.mail [email protected]