Conveying, Crushing, Screens & Feeders, Mobile Plant, Plant & Equipment
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Is modular plant the answer? Find out with our report.
Is modular the answer?
After a period of inactivity, modular crushing and screening plants are back in vogue in the quarrying market. Damian Christie canvassed three suppliers to the industry about the pros and cons of modular plant.
The concept of what defines a quarry operation has changed over the decades. Traditionally, the modern quarry is a fixed plant operation comprising primary, secondary and fine crushers, aided by screens, feeders and conveyors. All aggregate must be loaded and hauled from the rock face a typical distance of two kilometres to the fixed plant for processing and refinement.
However, the definition, size and scale of quarry operations now varies more than ever. In some quarries, the expenses of loading and hauling the aggregate and maintaining a fixed plant has encouraged some operations to process at the rock face with mobile plant. Some smaller quarries rely on tracked mobile plant alone to do the job of a fixed plant.
Other quarry businesses have transcended the notion of being bound in one place by becoming roving contractors, taking their mobile plant up and down the coast (both east and west) to process aggregate on behalf of local government and private enterprise. They set up their mobile plant and equipment in a quarry, blast, fragment and process the rock and then when the job/contract is finished will move onto the next quarry, taking their mobile plant with them.
Some quarry businesses – eg Boral, Holcim, Hanson, etc – which manage numerous quarries across the country are so inundated with orders that even they are required to contract out their work to keep up with demand. As a result, even where a quarry has fixed or mobile plant on-site, it may have to bring in more equipment to get the job done.
Tracked and wheeled mobile equipment is sufficient for supplementary orders or smaller jobs but what happens when a large order comes in that is beyond the scope of mobile equipment but cannot be handled by larger, fixed plant because other orders are in the pipeline? Various suppliers to the industry believe that modular crushing, screening and feeding plants may be the answer.
WHAT IS A MODULAR PLANT?
A modular plant is a processing plant for medium to long term crushing jobs. It has standardised, self-contained and portable crushing, screening and feeding stations and conveyor belts that are mounted on static steel work, equipped with automated systems and an independent power source. The plant is manufactured in large sections – or modules – that include walkways, motors, drives and other components.
The modules can be easily shipped to a site and rapidly assembled, without the need for foundations and civil works. Not only does the rapid set-up reduce costs and save time but it also makes it practical for the plant to be disassembled and relocated to another site in the future, whether that be to another rock face in the same quarry or to another quarry entirely.
All modular plants are equipped with the regular features of a fixed plant: primary stations (including hopper, grizzly feeder and jaw crusher), secondary and tertiary crushing stations (comprising cone crushers and horizontal and vertical shaft impactors), and quaternary and screening stations, as well as conveyors, washers and materials handling processes to link the plant sections together.
The versatility of the plant is that it can be easily reconfigured to fit the production of one specific product or to suit the processing of a range of multiple aggregate sizes. The numbers and combinations of crushers, screens and feeders within the plant can be customised to suit the operator’s requirements, ie screens and crushers can be added and removed at will to suit new applications. Most importantly for operators, modular plants are also capable of producing the type of output that one would expect of a fixed, rigid plant in a very large job, ie between 300 tonnes per hour (minimum) and up to 1000 tph.
Most modular plant suppliers offer diesel/hydraulic, diesel/hydraulic/electric or all-electric options for operators, depending on each operator’s individual requirements. Most plants will also feature an automated, air conditioned operator control room but individual unit controls can be supplied.
Today, modular plants are offered by reputable international suppliers to the industry worldwide, including Terex Mineral Processing Systems, Trio Engineered Products, Astec Industries, Metso and Pilot Crushtec, as well as Australian suppliers Global Crushers & Spares and Striker. While they are being used more in Australia in the mining industry than in quarrying, they have nevertheless been integral to a number of infrastructure projects in recent years. Modular plant systems have played major roles in the crushing of aggregate for the upgrade of Queensland’s Hinze Dam Stage 3, the Cotter Dam development outside Canberra, infrastructure projects in Gladstone, in Queensland’s north, and various mining projects throughout Western Australia.
Modular plant is not a new concept to the industry. It has been used on and off by quarry producers for the last three decades but there has recently been a resurgence of interest in the machines. Tony Barton, the eastern region sales manager for Astec Australia’s aggregate and mining division, says that contractors prefer modular plant to tracked crushing plant because of the “ease of the maintenance and lower operating costs”.
Morgan Bennett, the manager of Index Equipment & Machinery Sales, based in Brisbane, attributes this renewed popularity to the convenience of a “standard product in a pre-engineered way, with shorter lead times”. John Flynn, the sales director for Terex Mineral Processing Systems in Australia and New Zealand, suggests among customers, there is “increased acceptance of standard, transportable, self-contained crushing stations which operate as a system on a small footprint as opposed to large custom built crushing plants”.
“While operators enjoy the advantages of mobile plants, they also lament their shortcomings,” adds Flynn. “For many years, operators have asked for a solution that combines the advantages of both mobile and fixed plant and they are telling us that the modular concept suits their needs.”
All three suppliers to the industry are convinced that modular plants are now a superior alternative to their tracked and wheeled mobile cousins when it comes to commissioning plant for in-pit crushing. They argue that the modular plant features a wider range of equipment than traditional mobile equipment, including more heavy duty quarrying equipment (as opposed to lighter – or reduced weight for transport – equipment).
Further, this heavy duty equipment is still affordable, is easily transportable and can be assembled and delivered in quick time. The three suppliers also agree that a modular plant can offer better service access for maintenance and repairs than most tracked or wheeled mobile machines – there is no need for technicians to crawl into tricky, confined spaces to perform a service or enact repairs.
INTERNATIONAL CASE STUDIES
All three suppliers have impressive records with their modular plant abroad. Astec Australia distributes Telsmith and Osborn modular plants, Index EMS is the distributor for Trio Engineering Products’ modular skid plants and Terex MPS is marketing its own modular cone and jaw products.
In the US, one of Telsmith’s first major successes with modular plant occurred in the mid-2000s when Tilcon New York Inc purchased a New Jersey quarry whose reserves were depleted. With five to seven years of good reserves sitting under the existing crushing plant, Tilcon elected to commission a modular plant. It was not feasible to relocate the existing plant whose technology and support structures were impractical and obsolete and Tilcon also knew the crushing plant would need to meet the design criteria set forth in its business plan.
The plan set out production of quality cubical products at a rate of 10,000 tonnes per day, a small operating staff and the ability to relocate the plant economically after five years.
The Telsmith modular plant was the most effective solution. Built on a skid measuring 152 metres by 335m, Tilcon’s new plant was designed to produce five products simultaneously at 1000 tph. It comprised a Telsmith 3858 primary jaw crusher powered by a 224kW electric motor, three SBS cone crushers and three large Vibro-King screens. The plant ran in a single direction, with conveyor belts feeding down the sides, to minimise transfer points and wear areas.
The plant also included extra clearance for clean-up, large service platforms and one metre wide walkways in critical areas. There were also guard and safety rails built into the modules and wrap-around catwalks at the head pulleys to ensure maintenance crews could service the bearings from both sides of the conveyor. Astec Industries’ Controls Division provided Tilcon’s plant with automated plant controls that were linked to Telsmith’s Milwaukee production facility.
In Ndola, Zambia, Trio modular crushing and screening equipment, in conjunction with Pilot Crushtec machinery, has enabled a limestone crushing producer – Ndola Lime - to produce 100 tph of aggregate to feed that nation’s booming construction industry. The plant comprises a MJ2436 jaw crusher, a MC90 cone crusher, DD4815 and DD3615 double deck screens, a 20 metre MC800 conveyor, three 16m MC800 conveyors, four 16m MC600 conveyors and a CRP36 permanent overband magnet.
The 13-piece modular plant was delivered in May last year and was up and running a month later. With Ndola Lime receiving orders for more than 50,000 tonnes of aggregate, the plant was extremely busy for the first two months of operation and with constant feeding, it was able to achieve up to 150 tph. The modular plant ultimately has produced product ranges of 0-7mm, 7-14mm, 14-19mm and 19-30mm.
This was the second lime project in Zambia that Trio and Pilot modular plant had assisted. In July 2010, another Ndola-based limestone producer – Zamm Imports – commissioned an 18-piece modular plant, which included a MJ3042 jaw crusher, a DD4815 double deck screen, a MC130 standard cone crusher, a MC130 short head cone crusher and a TD6118 triple deck screen. This plant was initially required to crush up to 200 tph of aggregate and was producing 0-5mm, 5-10mm, 10-19mm and 19-25mm of limestone aggregate.
Trio modular plant is yet to work on such prolific projects in Australia but Index EMS has already commissioned a two-stage Trio metallic ore crushing plant for a Queensland operation. The plant consisted of a TF4616 feeder, CT3042 jaw crusher, TIO6203 inclined screen, TC51 cone crusher, and an assortment of transfer, feed, portable jump and stationary overland conveyors, as well as radial stacking conveyors with a separate surge feed hopper. This plant was paired with existing on-site equipment to complete a 120 tph heap leach crushing circuit.
“Trio and Index used a collaborative approach to partner with the owner to design a modular system that combined standard features with the plant’s custom requirements,” Bennett explains. “This approach allowed us to rapidly deliver an economical solution that enabled the customer to quickly re-activate a dormant mine and begin generating revenue from his uncrushed ore reserves.”
At the recent edition of Hillhead, held from 19 to 21 June this year in Buxton, UK, Terex MPS exhibited two of its latest modular products: the MC1000 cone and the MJ42 jaw. The 1000mm (40”) cone module is designed to handle an all-in feed for continuous crushing and it has an unrestricted feed opening and a full range of configurations for short and long throw. Its all roller bearing design is intended to improve crushing efficiency and it also features a hydraulically adjustable closed side setting (CSS), easy manganese changes and a weather-protected control panel with user-friendly controls.
The MJ42 module features a JW42 jaw crusher with its hydraulically actuated wedge system which allows CSS to be made quickly and easily. It also features a three-piece boltless hopper and spring-mounted vibrating pan and grizzly feeder.
Both modules are designed to bolt together and operate interchangeably, with little requirement for on-site wiring. Designed with logistics in mind, each module, including all components, can be transported in one container each. The MC1000 and MJ42 plants are also available in Australia.
At the show, Jason Talbot, Terex MPS’s global product line director said that these modular plant demonstrated “our ability to listen to the customer and bring products to the market that enable our customers to choose ‘ready to work’ modules to create the plant they need for a variety of applications”.
The success of all three companies’ modular plant in a range of different quarrying applications and climates, is good cause for optimism that modular plant can work in Australia too. The challenge for these three suppliers – and for other suppliers and distributors of modular plant in the Australian market – is to convince quarry operators that modular plant is a worthy investment and can outperform and indeed supersede the reliability and consistency of tracked and wheeled mobile crushing plant and equipment.
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Posted August 01, 2012
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