Sunday 11th Apr, 2021

Powder handling system rejuvenated at Fletcher International

Fletcher's installed hopper and pneumatic conveying vessels.

A powder handling system that ran for 11 years from 1997, handling limestone and soda ash, has been refurbished and brought back to life for a different application in Dubbo involving cement and slag.

Fletcher International Exports has large pastoral holdings in Queensland, New South Wales and Western Australia, with abattoirs in Albany and Dubbo. It is a private family-owned company that has grown substantially over the last 35 years. Its origins relate back to Roger Fletcher when he started as a drover in outback NSW.

The company supplies sheep meat, wool and by-products to over 90 countries around the world.

From its inland abattoir location of Dubbo, it rails its product to seaports for export. Fletchers recently purchased its own rolling stock of three locomotives and 62 wagons to run between Dubbo and Botany three times a week. The rail also transports the company’s grains, pulses and livestock.

After its investment in rail handling facilities, Fletcher has recently invested in a system for supplying a cement/slag product to nearby mines.

 

View of Fletcher's silo installation.
View of Fletcher’s silo installation.

 

Cement and slag arrive from overseas in bulk bags at the railhead, where the new handling system is installed. The product enters the plant in bulk bags, then is unloaded and mixed, and ultimately conveyed to silos for take away by pressurised bulk powder tankers to mining ventures.

This is an interesting re-application of a powder handling system that was originally installed by Kockums Bulk Systems for Kalari Pty Ltd in Laverton Melbourne during 1997.

The system was designed to load silos with powders that had been transported to site in tippers and unloaded into defined bays in a warehouse. The product was recovered from the warehouse by use of a front-end loader fitted with a large bucket to dump product through a wall opening into a receival hopper mounted over three pneumatic conveyors.

The system separately handled both limestone and soda ash for use in the glass industry, having one silo dedicated to each product. The installation operated with either product at a 50 tonne per hour transfer rate to the silos using three pneumatic conveying vessels (PCVs) mounted under the hopper, running on a sequential basis.

 

Kalari silo installation.

 

Effectively, one vessel was being filled, while the next was nearing the end of discharge, and the third vessel filled on standby, ready to come on line overlapping the end of the previous vessel cycle. This was to achieve continuous conveying in the discharge line to the silos.

To ensure fast acting cycling of the vessels they were fitted with Posi-flate inflatable seat butterfly valves which dramatically increase the life of a butterfly valve, while also having a very quick open-close action.

The silos were designed for discharging into B-double bulk road tankers from either silo in just 11 minutes, including the time for moving the truck forward for discharge from a single silo spout.

The rate was achieved using Kockums’ SonoPulse silo aeration system which also initiated mass flow in silos that are designed with a shallow cone angle. The shallow cone offered a significant reduction in the height and the cost of the silo complex compared to a true mass flow deep cone design.

The use of the SonoPulse was vital to have the soda ash discharging fully under mass flow conditions, as the minimum time in the silo is critical to prevent agglomeration of the product.

The Fletcher site confirmed that this loading rate of the road tankers was also being achieved with the relocated system.

A Kockums KH50 compressor with a 55 kW motor was installed for the 200 kPa pneumatic conveying air supply in 150 mm conveying line.

 

Original Kalari PCV nest.
Original Kalari PCV nest.

 

The system ran for about 11 years before it became redundant to requirements.

Fletchers purchased the second-hand Kalari system and contacted Kockums Bulk Systems for advice on the application for handling quite different products, and for a different process.

Kockums was engaged in 2014 for services including design calculations, suitability of purpose, functional description, operational manuals and commissioning assistance.

Commencing a new operation for the equipment meant the need for refurbishment of valves, air filters and SonoPulse systems to bring the equipment back to ‘as new’ condition.

On a recent visit to site, Ivan Price, director of Kockums and Kalari concept designer in 1997, met Sean Magnusson, operations manager for the Fletcher International site.

“I was pleased to see the quality of the installation, which is achieving the high rate of 32 tonnes per hour throughput from product arriving in bulk bags. It is good to see a system rejuvenated and performing well, meeting a new need,” said Price. “I congratulate Fletchers on their engineering expertise and how they handled the process in an efficient and effective manner.” For its part, Kockums has extensive experience and history in powder handling systems.

Price continued: “I was impressed that the original Kockums KH50 pneumatic conveying compressor had seen over 10 years’ work in the Kalari system without a strip overhaul and was advised by Sean that they had taken an end off and found the seal bars in good condition so there was no need for a major service at this time.

“The outcome has been that the system hardware and silos that were purpose-built for one application, were later able to be successfully adapted for an alternate need in a different industry.”