Until the end of 2007, the market value of sulphur had remained depressed at $100 a ton, and for one of the longest periods ever. This made the cost of recovery uneconomic so, it was just stockpiled as a result. However, when the price increased five-fold to $500 a ton at the end of 2007, recovery became a profit opportunity for the owners of an oil refinery in Kenai, on the North Slope of Alaska, USA. Sulphur is a by-product of diesel fuel that’s applied to the land as a fertiliser amongst its many other uses. Having accumulated 36,000 tons of sulphur, the owners of the oil refirnery contacted AIMM Technologies, Inc for assistance. AIMM is a Texas based oil industry service-company with 15 years recycling/processing experience and an excellent track record in Alaska.

Customer requirements

“Alaska is a logistical nightmare in which to recycle petroleum by-products such as sulphur,” confirms Brooks Bradford, President of AIMM Technologies. “Sulphur is a hazardous material that can easily catch fire. For this contract, we had to bag the sulphur, move it to a storage site, move it from the storage site by truck to a port and then load it onto an ocean vessel for delivery to market. When we got the go ahead to recover the sulphur, we concluded that the best way was to use bulk bags. For this, we needed a means of filling them. One specific requirement was that the bagging facility had to be easy to dismantle for use at another sulphur recovery site once recovery at this site was complete”, Bradford confirmed. “After researching various suppliers, we selected Spiroflow Systems Inc, who were able to meet our tight delivery requirement of four weeks - with installation and start-up taking no longer than an additional two weeks. We got the job in mid-February 2007 and wanted to startup the facility by the end of March, a very tight schedule,” Bradford added. “Spiroflow was the only supplier who could meet our tight deadline. Most suppliers we contacted wanted a 12-week delivery time or more.”

Spiroflow solutions

Our US sister company, Spiroflow Systems Inc, recommended two of its ‘Spirofil’ Model C1-2 Weigh Fillers which are specially designed for pallet loaded Bulk Bags / Flexible Intermediate Bulk Containers (FIBC’s). The Model C1-2 is ideal for FIBC’s of 2,000 to 4,000 lbs (approximately 1 to 2 metric tonnes) capacity that are removed from the filler on a pallet when full. Model C1-2 Fillers incorporate a ‘weights and measures’ approved weigh platform and those supplied to AIMM were complete with integral powered rollers for fast and easy removal of filled bags. The FIBC’s at Kenai each held 3,300 lbs of material, were 3.0 feet (0.92m) in diameter and custom made of conductive polyester for the safe handling of sulphur. Once filled, the FIBC’s were powered off of the fillers onto gravity roller ‘queuing’ conveyors where they awaited removal by forklift truck.

The two Bulk Bag Fillers were customised before dispatch from our plant in Monroe, North Carolina. The power supply, for example, had to be modified to US Class 1, Division 2 since an electric spark could ignite the sulphur.

Once manufactured, the two Bulk Bag Fillers were assembled onto a skid and delivered by truck to the Kenai, Alaska site. It took the truck 5 days to complete the journey. We also sent a Commissioning Engineer to the site for two weeks to supervise installation, commission the filler and to train the operatives.

“We appreciated the extra effort by Spiroflow since we were not familiar with bulk bag fillers,” Bradford noted. “So, we needed training too.”

The Bulk Bag Filling System

The Bulk Bag Filler facility at the Kenai petroleum refinery comprised a 28 foot high frame to support a feed hopper, the two Spiroflow Model “C1-2” Bulk Bag Fillers and two roller ‘queuing’ conveyors. Full, 3300 lb (1.5 metric tonne) capacity bags were driven off the fillers onto gravity roller conveyors. Using stevedore straps, forklift trucks picked up the bags to take them to the storage yard or to load them directly onto trucks for delivery to the dockside in the port of Homer, some 3 hours drive away.

AIMM Technologies designed the 28-foot high support frame and the hopper into which the sulphur from the sulphur stock yard was loaded, whilst Spiroflow was responsible for customising two of their “Spirofil” Bulk Bag Fillers and designing a square ‘trouser leg’ chute system that attached to the bottom of the feed hopper. Control of the sulphur from the feed hopper down either of the trouser-leg chutes and into the bulk bag fillers was by way of a series of diverter valves and slide gate valves.

300 Bags of Sulphur Processed Each Shift

According to Jeff Deese, Vice President of the Alaska Division for AIMM Technologies, the facility was in operation for 14 weeks from the end of March to mid-July in 2008. The Kenai facility had 10 people working each 8-hour shift, four of whom were at the bagging station.

The facility averaged 300 bags a shift, reaching a high of 404 bags on one of the shifts. Three hundred bags a shift is an average of 18.75 bags per hour per filling machine. In all, 36,000 tons of sulphur was recovered in 27,000 FIBC’s.

Deese said that customer support from Spiroflow Systems was phenomenal. “Not only did they send a Commissioning Engineer to site for two weeks to install, to start-up the system and to train us how to use it, the system was delivered on time.” Deese added. “Company engineers were easy to work with and available 24 hours a day, an important feature due to the time difference in Alaska. We couldn’t have done this without Spiroflow’s help and availability.”

Bags were taken from the storage facility in one of four trucks that moved bags continuously to the Port of Homer, Alaska, about three hours from Kenai. The sulphur was sold at Homer to a third party who shipped it to an inland river port in China where it will be used mainly as fertilizer.

Upon completion of the contract at Kenai, the bulk bag filling facility was dismantled and reassembled at another sulphur recovery site in Canada where it was converted to handle 4,000 lb bags instead of the 3,300 lb bags handled at the Kenai facility, an increase in capacity of 21%.