In 2011, the Central Highland Regional Council, based in Emerald, Queensland, commissioned Scope Engineering Services, based in Toorbul, in northern Queensland, to install a modern, state of the art crushing plant at the nearby Shepton Quarry to meet the demands of the local coal mining boom.
The quarry site at Shepton is 14km east of Capella and about 45km north of Emerald. It sits on a basalt plug of 40 million tonnes of high grade reserves. The resource quality is one of the best, if not the best, west of the Great Dividing Range in Queensland.
The site was initially developed in 1993 by the then Peak Downs Shire Council, a small rural shire council based at Capella.
A small production plant was established on-site which was located directly on top of the best part of the resource.
In the 1970s, the surrounding areas became the hub for what is now termed the Bowen Basin coal tenements with the associated escalation in industry activity. The council then commenced production of concrete and sealing aggregates at the site.
This plant was progressively upgraded over time until the year 2000 when it consisted of a 36? x 24? jaw and two Kawasaki 1000 cone crushers and associated vibrating screens which had a production capability of approximately 120 to 150 tonnes per hour (tph).
A significant amount of the road aggregate for the mine sites is produced on the quarry site by contract portable plants if suitable deposits were able to be sourced but in general most of these deposits are not of suitable quality to yield top quality road construction materials or concrete aggregate.
In 2011, the quarry produced half a million tonnes for export and was expecting to increase this to three quarter of a million tonnes in 2012.
The sales catchment area for Shepton is within a 200km radius and as demand increased, the then Peak Downs Shire Council considered how best to update the site and increase production.
REVITALISING THE SITE
At around that time, the then Queensland State Government announced a forced amalgamation of clusters of small local authorities into larger governance bodies in the guise of efficiency improvement.
The Peak Downs Shire Council then became part of what is now Central Highlands Regional Council (CHRC) which was the amalgamation of four local authorities in Bauhinia, Duaringa, Emerald and Peak Downs.
This is one of the largest local authorities in Queensland. The Central Highlands region includes the towns of Emerald, Sringsure, Rolleston, Duaringa, Blackwater, Capella and Tieri and four townships in the Sapphire Gemfields. It extends over an area of 60,000km2, and has a population of more than 29,500 residents.
Central Highlands Regional Council has a large number of existing and proposed coal mines within its boundary and thus a high demand for quarry product.
Central Highlands Regional Council immediately recognised the potential financial benefit by upgrading the crushing plant and becoming commercial in the operation. This would assist in providing a much needed contribution of revenue flow to Council to support the other revenue streams and provide the infrastructure required for a rapidly developing area.
External advice was engaged to assess and recommend options on the project.
Council had several options:
i. To partially upgrade the old plant.
ii. To construct a modern state of the art 400 tph plant.
iii. To lease or sell the site.
Option (ii) was chosen and a geological investigation was undertaken to confirm the extent of the resource so that the location and construction of the new range plant would not sterilise any of the reserves.
As the market from the site is in the 400,000 to 500,000 tonnes per annum range, the decision was made to construct a 400 tph crushing plant. On the basis of 2000 crushing hours per annum by 400 tph, capacity would yield 800,000 tph at 100 per cent availability or at 90 per cent, allowing for availability and efficiency reductions of 720,000 tph.
Aggflow modelling was undertaken which indicated that the cone crusher selection in the 275kW to 300kW range would fulfill Council?s requirements.
The crushing plant conceptual design was developed around producing all products without the requirement to change screen cloths. This is done by either reversing the direction of conveyors or flop gates in screen discharge chutes.
Specification and tender documents were prepared and tenders called for the design and construction of the crushing plant.
Tenders had the option of a turn key proposal or any of three sections of the project, including:
- Structural and civil works.
- Supply of key items, crusher, etc.
- Complete electrical works.
Thirteen tenders were submitted with a variance of 80 per cent between lowest and highest.
A rigorous assessment process was undertaken to compare and value the proposals with specific emphasis on the experience of the tenderer, completed projects of a similar nature, Australian product, product support and pricing.
The tender was not awarded on a turn key basis as this was the most expensive option and did not permit selection of what might be considered the best available options.
The contracts were awarded to Scope Engineering (structural and civil works), Terex Jaques (crushers and key components) and J&P Richardson (total electrical installation).
INSTALLED EQUIPMENT ?AND PRODUCT OUTPUT
The installed equipment comprised:
- A 100 tonne PRF receiving bin.
- A ST47 Terex Jaques jaw crusher.
- A J50 Terex Jaques secondary crusher.
- A J50 Terex Jaques tertiary crusher.
- A Canica rotor autogenous VSI.
- A 16? x 6? x 3? deck scalping screen (single deck screen).
- A 20? x 8? x 3? deck sizing screens Jaques torrent (multiple screens).
- A Syntrontech electro magnet vibrating feeder (four-deck vibrator feeder).
- The end products included:
- Armour rock.
- Gabion rock.
- Rail ballast.
- 20mm and 10mm concrete aggregate.
- Manufactured sand for pre-mix concrete.
- Simultaneous 16mm, 14mm, 10mm, 7mm and 5mm sealing aggregate.
- All grades of road pavement material.
ISSUES EXPERIENCED ?DURING THE PROJECT
There were a number of problems experienced over the life of the project, including:
? The onset of the global financial crisis which delayed awarding the tender due to insufficient CHRC/State Government funds.
? A natural disaster in the form of extremely high rainfall, which delayed the project.
? Very substandard customer service with regards to available power supply and relocation of existing service. This resulted in CHRC having to acquire a 2000kVA generator that shares the energy requirement with a 750kVA Ergon mains power supply.
Source: Scope Engineering Services Pty Ltd