Stockyard for bulk materials

Material or article handling – Coal storage type

Reexamination Certificate

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Details

C198S508000

Reexamination Certificate

active

06508615

ABSTRACT:

TECHNICAL FIELD
This invention relates to an uncovered storage facility for stockpiling bulk materials. The invention is particularly applicable to an import or export terminal for bulk materials and will be described mainly in relation thereto, but it is to be understood it is applicable to any facility providing a stockyard for bulk materials. Examples of bulk materials commonly stored in such facilities include coal, iron ore, limestone and bauxite.
BACKGROUND
In typical export terminals, materials arrive by road or rail transport and are loaded into ships holds whereas at typical import terminals the reverse occurs. As the volumes handled by road or rail shipments are much smaller than those handled by a ship, and given that materials may not be received at the time they are needed for loading, a buffer of the materials is usually established in stockpiles in a stockyard at the import or export (or intermodal) terminal. Such stockyards generally involve large land areas and the provision of facilities for handling the bulk materials between their arrival at a terminal and their delivery from the terminal. Such facilities generally involve receiving, stacking, blending, reclaiming etc of the materials.
Due to the nature of Bulk Materials Handling, these terminals tend to be quite large. For example “large volume” terminals may handle in the order of 1,000,000 to 100,000,000 tonnes of throughput per annum (examples in Australia are coal export terminals at Newcastle in New South Wales, Gladstone in Queensland and Drylmple Bay and Hay Point at Makay in Queensland; iron ore export terminals at Dampier and Port Headland in Western Australia; and the cement clinker facility at Gladstone in Queensland). “Medium Volume” terminals may handle in the order of 10,000 to 10,000,000 tonnes per annum.
Known import or export terminals, which provide facilities for stockpiling bulk materials, are generally purpose built to handle only one or two types of material, or materials for a particular industry.
The present invention provides a stockpile facility for a terminal for s tacking, storing and reclaiming materials in which economies are achieved by its compactness allowing an efficient utilisation of machinery and by its flexibility in its use for a multitude of materials.
The efficiency of operation of a bulk materials terminal is optimised by appropriately matching all its operations generally in relation to an intended throughput capacity and the method of operation. There are two main methods of operation, namely “cargo assembly” and “bulk material banking”, and they have different requirements for material buffering and thus stockpile sizes between delivery of a bulk material to the stockpile facility and its departure therefrom.
Cargo Assembly involves delivery of minimum bulk material to an export terminal on a just-in-time basis to fill the cargo requirements of a ship being expected in the port within a certain time frame, typically three to eight days. That is, the deliveries begin at a sufficient time in advance of the bulk material being needed for loading to build a sufficiently large buffer for the particular ship to be loaded without interruptions. The arriving material may be stacked in and reclaimed from several distinct stockpiles because blending may be required during loading (involving reclaiming from multiple stockpiles) or because the ship is to be loaded with a multiple of distinct cargos. Generally the stockpiles with this method are relatively small.
Bulk Material Banking involves delivery of bulk materials to an export terminal on a regular basis and maintenance in a stockyard of a minimum inventory of a given material or grades and blends thereof. The minimum inventory is typically a specified percentage of the annual or monthly throughput of the given material. Generally this involves the stacking of all cargoes for all ships of the given material together in a minimum number of distinct stockpiles, rather than stacking each cargo for each ship. Thus with this method the stockpiles are significantly larger than for the cargo assembly method.
The present invention seeks to provide a stockyard facility which caters for and achieves efficiencies primarily in relation to Bulk Material Banking. However it may be beneficially used—and flexibly over time—for either Cargo Assembly, or Material Banking, or Cargo Assembly together with Material Banking.
Principal determinants of the capital, operating and maintenance costs of an import or export terminal are
the boom lengths for the mobile stackers and reclaimers (the cost and mass, and therefore wear and tear, of these machines is proportional to the square of the length of their booms),
the throughput capacity ratings for each of the machines and conveyors.
length (and width) of stockyard for a given storage capacity.
The layout and dimensions of the stockyard in a terminal has a significant influence on these determinants. For example the pad width, that is the width of a stockpile, relates to the boom length of the reclaimers and stackers. Generally the total volume of stockpile that is needed is sized according to the intended number of distinct stockpiles needed to accommodate distinct materials or material owners, throughput capacity and method of operation (that is, Cargo Assembly or Bulk Material Banking). A cross-sectional size for the stockpiles is then chosen to optimise between the angle of repose of the bulk materials to be stored and the horizontal (and secondarily the vertical) operating range for the stacker and reclaimer machines. These parameters define the total pad length (and therefore area) needed which must also be sized to allow for unhindered operation between stackers and reclaimers servicing individual stockpiles. The total pad length and area, and volumetric capacity, can then be satisfied as either a single and/or a multiplicity of pads. Clearly, the provision of a stockyard requires a large area of land and an arrangement which minimises that land requirement-without compromising the efficiency of the stockyard operations is highly desirable, particularly where large parcels of land suitably located are scarce.
The capital, maintenance and operating efficiency of a stockyard depends on several parameters. For example, narrower stockpiles allow for shorter boom lengths for the stacker and reclaimer machines and thus lower capital, maintenance and operating costs. Shorter length stockpiles allow shorter rails (on which the stackers and reclaimers move), shorter conveyors and related civil works and thus reduced capital, maintenance and operating costs. Shorter stockpiles also lead to reduced re-locating distances for the machines and thus reduced operating and maintenance costs for them, and thus may also reduce the delay times and thus costs in receiving/unloading/stacking bulk materials and in reclaiming/loading/despatching the bulk materials. Other factors relate to the pattern with which a stockpile is stacked (for example, windrow stacking, coneplying or chevron stacking) which can affect the uniformity of recovery of material from a stockpile by a reclaimer machine. The uniformity of material recovery is also affected by the reclaiming method, three of which are commonly used, namely (i) the slew bench cut and pilgrim step, (ii) travelling bench cut and (iii) combined slew and travel bench cut. None of these methods allows the reclaimer to always reclaim at a uniform rate.
A stockpile for which a given volume is presented with a predetermined and more generally rectangular cross-section (compared with a more triangular cross-section of a traditional stockpile) represents a stockpile for which each relative sub-cross section presented to the reclaimer bucket wheel and for which the average of all sub-cross sections presented to the bucket wheel have a higher material to void content than traditional stockpiles. This results in both more effective reclaiming (ie. the reclaimer is able to more often encounter a higher material to void cross-section over the course of reclaiming a stockp

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