In each trailer, AI Automation implemented Mitsubishi Q series and FX series PLC equipment as well as Mitsubishi HMI touch screens. Mitsubishi’s variable speed drives were used to provide finer control, as were Mitsubishi’s variable speed drives.

At final count, the full plant consisted of one primary jaw crusher, one tertiary cone crusher, one secondary cone crusher, one fines vibratory multi-deck screen, one scalping multi-deck screen, and three height-variable roving radial stackers with ultrasonic material level sensing.

Each section of mobile plant can be independently operated, or coupled together for various plant configurations, for example to deal with different material grades or types.

Communications systems

Local configuration and control for each trailer was afforded by the PLC system and touch screens present in every unit. This is in addition to the standard central control.

“The main control room with 15-inch touch screens is where the client can oversee the lot,” Heath explained. “The screens themselves are quite intelligent: they handle the transmission of data between the systems and works quite well.”

All the trailers provide operational feedback of critical system pressures and temperatures back to the control room HMI unit, and the system is expandable. For example, video plant surveillance can be installed later, as can direct remote access capabilities which will allow even more flexible monitoring and configuration.

Communications between the trailers and control equipment is handled by radio Ethernet, which eliminates the need for pesky re-cabling when the modules are reconfigured for new applications.

Given the application, the speed and reliability of radio Ethernet technology was more than satisfactory for the project.

“The data speed varies depending on what we’re transmitting,” said Heath. “We do not shift a large amount of data around. It was more necessary to bring the system together into a single HMI screen and controller; we’re only periodically looking at the information or sending out bits of data.”

Mobility and flexibility

Mobility was a big consideration for the project, with the modular nature of the trailers allowing the client to mix and match the plant according to its needs. For example, the client can choose to exclude plants when they are not necessary for the process.

“[With this project], you can change the plant’s configuration easily. [With] a fixed plant, you can’t do that, you’re stuck with what you’ve got, and it’s a major exercise to reconfigure,” Heath told PACE.

“This plant could be reconfigured in a number of ways, depending on what grade of ore you are processing, or what you’re trying to achieve.”

The self-contained nature of the plants was boosted by the use of diesel electric generators on each trailer, meaning the system did not have to be tethered to a central powerhouse, a fixed power plant or power source, further improving the flexibility and configurability of the solution.

According to Heath, a system of the scope specified would normally be a fixed plant, but the need for two or three different configurations meant a fixed plant was out of the question.

“You wouldn’t be able to achieve that configurability with a fixed plant – the plant would have been massive,” Heath said.

While the trailers lend themselves well to being transported, the project in Western Australia was intended for just one mine site. However, Heath acknowledged the potential of such a system for higher end sectors, where the plants may need to be shifted to various sites on a needed basis, or around the site.

In addition to the flexible configuration of the plant, additional control over processes like material feed control, screening efficiency and stock piling was provided by the use of Mitsubishi variable speed drives.

This combination of equipment allowed the client fine-grained control over its operation, with the processes entirely adjustable according to the grade of ore it had to deal with. The variable speed drives also provided energy savings, ensuring a full tank of diesel lasts as long as possible.

Reliability matters

In mining applications, with its tough conditions and when dealing with ore of various hardness, reliability is key – especially when any downtime can represent millions of lost dollars.

By all accounts, the Mitsubishi equipment package has taken the 800 to 1,000 tonnes per hour production rate, extreme heat, dust, vibration and precipitation in its stride, with reliable and efficient performance.

Heath swears by Mitsubishi equipment. “I personally used Mitsubishi for some 15 or more years, and its systems are highly reliable,” said Heath.

“Their equipment is advanced, and is considered a world-wide market leader. Certainly it has a reputation of reliability and one that is well-earned.”

Reliability is certainly good news for the client. Depending on the grade of ore being crushed, these plants can be set up and run for ten years or more.

For distributors, happy customers are a good thing, but Heath wryly points out that this reliability means rarely will he get sales out of replacing broken equipment. Most of AI Automation’s work now comes from either expansion or superseded equipment replacement.

Many advantages

Heath summed up the advantages of the project for the client as “mobility, reliability, configurability and cost”.

Through the use of Mitsubishi’s equipment and control technology, AI Automation was able to build a solution to address the client’s need for a flexible solution.

By mounting the plants on self-powered trailers, the firm opened the door to a solution which can be quickly and cost-effectively rearranged to deal with a wide variety of tasks and material.

This innovative form factor, along with the proven reliability of the equipment, meant AI Automation’s client has been blissfully quiet about the project since its delivery.

Preparation is the key

The revised mobile jaw crusher guidance notes make a number of recommendations. Perhaps the most important of these is the preparation of material prior to crushing. “The segregation of construction and demolition waste prior to crushing is vitally important,” Button said. “It helps ensure a high quality and saleable end product and it is the only real way of ensuring that tramp iron doesn’t make it into the crusher jaws.”

There are numerous solutions to this pre-sorting conundrum including pre-screening systems, hand-picking, and even pre-processing with a crusher bucket, for example. All will have their place in certain applications but all are still likely to require a fall-back position.

“The Health and Safety Executive believe that a platform-mounted mini excavator equipped with a hydraulic breaker or a dedicated pedestal-mounted breaker boom negates the need for a man to be stationed on the crusher during operation,” Button said. “But once again, it is import to differentiate between a demolition site and a quarry. In quarries, the crusher isn’t subject to height restrictions during transportation. Quarries also have plenty of room to spare while on an average demolition site, space is at a premium. These are important issues that need to be addressed.”

Shaking all over

Another key issue to be addressed by the new guidance notes is the often emotive subject of whole body vibration. The HSE has already made it quite clear that operatives stood on a working mobile crusher would be considered to be exceeding whole body vibration limits and to be well above action levels for noise emissions.

“We have been aware of the long-term effects of whole body vibration for a number of years, although primarily related to other types of mobile plant and equipment. As the demolition sector embraces ever more efficient recycling methods, the use of mobile crushers will continue to become increasingly widespread. We will, therefore, have to address the subject of vibration on these highly specialised machines as well. New technology such as remotely-controlled operation and CCTV cameras positioned within the crusher chamber may ultimately help make mobile jaw crushers safer,” summarised Button.

“But, for the time being, it is our responsibility as an industry to help protect our operatives. And the revised guidance notes will play a key role in that task.”

Produced in conjunction with crushing equipment manufacturer Sandvik Mining and Construction, the revised guidance notes address a number of potential hazards associated with track-mounted mobile crushers.

“Although thankfully not on our members’ sites, there have been fatalities involving jaw crushers and the Health and Safety Executive is taking a very keen interest in their safe operation,” said NFDC chief executive Howard Button.

“The HSE is seeking to outlaw the practice of having an operative on the machine’s platform while it’s in operation to protect him from being struck by an excavator’s bucket, avoid possible whole body vibration, limit exposure to noise and dust, prevent him falling into the crushing chamber and to avoid him being hit by material ejected from the crusher’s jaws. We are similarly keen to avoid these potential hazards but we are also keen to ensure that any guidance reflects the nature of our business and are not simply a set of modified rules derived from a quarry guidance.”

Quarry vs recycling duties

There are numerous differences between a jaw crusher in a quarry processing virgin aggregate and a jaw crusher on a demolition or recycling site processing a variety of materials. Key among these is the presence of steel, tramp iron and other contaminants in the feed material.

“The primary reason a man is stationed atop a track mounted mobile crusher is to watch for materials that might cause a blockage such as steel reinforcing bar, or worse, a girder section. That is something quarries simply don’t have to contend with,” Button asserted. “These are, however, ever-present dangers in a demolition or recycling application and operators have to be vigilant to avoid blockage, bridging and damage to conveyors. Our guidance notes reflect the differences between these two distinct applications but are still designed to safeguard our operatives.”

Sandvik launched the new and innovative designed QJ241 tracked jaw crusher. Purposely redesigned in order to accommodate the emissions-compliant engines in accordance with the new 2011 Stage 3B / Tier 4i Engine Legislation, Sandvik decided to also take this opportunity to redevelop and upgrade its best selling compact jaw crusher to create one of the most technologically advanced tracked crushers in the market. The upgraded model incorporates the class leading characteristics of its predecessor, the QJ240, such as the high performing powerful 1000 x 650 mm jaw with hydraulic CSS setting, reversible jaw for relieving blockages, automatic central lubrication system for reducing maintenance time, dust suppression, overband magnet and side conveyor but now includes many additional outstanding features as standard which will set it apart from the competition.

One of the most advanced benefits to the customer is the addition of a raise and lower facility on the main conveyor. The conveyor can be raised and lowered for transport and will give increased clearance on the main conveyor for removal of rebar which will make it the ideal choice for recycling applications. It has also been extended to give an increased discharge height enabling enhanced stockpiling capabilities.

New features:
• A new hydraulic control system which will allow greater efficiency and ease of access and maintenance as all controls are located at ground level
• Level sensor fitted to the jaw inlet to optimize feed rate into the crusher
• Improved load control system for the feeder drive to ensure continuous, uninterrupted crushing
• Speed wheel fitted to the main conveyor to stop the feeder avoiding the need to dig out a heavily loaded conveyor
• Hydraulically driven cooling fan with auto reverse to back flush dust from the radiator
• Enhanced fuel economy for lower cost of ownership and a reduction in emissions by upto 45% for a reduced carbon footprint
• Capable of operating in the most hostile environments with a 50°C ambient temperature without any oil changes

The upgraded model has been redesigned with ease of operation in mind. Operators will find the machine much more user-friendly as it has a full PLC control system with colour screen for visual data output and greater access around both sides of the powerpack for easier maintenance and service. The diesel tank and smaller hydraulic tank have inspection covers and have been relocated to the front platform of the machine for improved access and the pipe work is now fabricated from steel to give a maintenance-free sealing solution and better heat dissipation.

Its heavy duty tracked chassis now driven by proportional remote control and hydraulically folding hopper enable a quick-set up time and although purpose designed for the recycling industry, the QJ241 is equally productive in quarrying applications.

These days there are lots of mining projects all over the world, like the Malaysia, Australia,Chile and so on. So there is a great demand of the mining equipments from the clients.However, there are some changes compared with the demands before. For example, thecrushing equipments for the mines. Several years ago, most of the clients prefered to the stationary type, which is very firm. Now most of them are changing ,and choosing the mobile type crushers, which is very easy to build and convenient to move from one sites to another. Nowadays, they are good sellers in all the mining equipments.

Kefid machinery is specialised in designing and manufacturing the mobile crushers in China. They have a strong team to carry out this, and are the biggest and most famous manufacturer in China. The workshop of kefid machinery is more than 120,000 m2 . Usually the monthly production is about 15-20sets mobile crushers. Their mobile crushers are working all over the world. If you are interested in themobile crushers, you can ask them and find the sites near your country for a visit. And then you will find the qualtiy and excellent service.

For more details, you can contact us online or send email to sales@kefidinc.com now.