Containing dust contamination

Paul Boughton

Handling materials poses many risks, dust explosions being one of the most serious. New developments in dust handling equipment are helping to mitigate this hazard. Sean Ottewell reports

Minimising dust contamination when filling and shifting millions of tonnes of powdered ingredients through a factory is challenging for all manufacturers, but there are innovative new solutions available on the market.

One such solution has been developed by Spiroflow. Initially developed for the handling of food and pharmaceutical ingredients, the T2 Angled Bulk Bag (FIBC) Discharger provides an air-tight operation which empties product with the minimum of residue and has angled framework, not horizontal flat surfaces, reducing settlement and saving time on cleaning.

This latest equipment is suited for a range of materials ranging from baby formula milk, sugar and flour to pharmaceutical powders and granules. Its novel construction stops fine dust sticking to any part of the discharger resulting in improved hygiene.

Unveiled for the first time by Spiroflow to visitors at this year’s Foodex and Interpack shows, the company says it is probably the first kit of its kind that has been especially designed in the UK to help avoid issues caused by dust residue. 

Dust in a factory environment can prove hazardous so manufacturers must have systems and equipment in place that adhere to the European Union’s ATEX Directive 1999/92/E, which has been implemented by the Dangerous Substances and Explosive Atmosphere Regulations 2002 (DSEAR) Act in the UK.

These regulations require that employers classify places where explosive atmospheres are likely to occur – such as in the form of combustible dust generated by processes such as flour milling and sugar grinding – and implement protective measures and select appropriate equipment for use in those environments.

Spiroflow’s products for conveying and bulk handling are designed and built to USDA standard and meet regulatory requirements for transporting and handling powders and other materials in potentially hazardous conditions. The company offers the food and pharmaceutical sectors innovative equipment that will help to eliminate material flow problems and dust contamination that can also lead to potentially dangerous blockages in factory piping or tubing applications.

In addition to bulk bag dischargers, Spiroflow manufacturers bin activators, flexible screw conveyors, aero mechanical conveyors, tubular cable and chain drag conveyors, vacuum conveyors, bulk bag fillers, ingredients handling and weighing systems. It also supplies state-of-the-art control rooms.

Tackling seams and folds

New from Flexicon is a dust containment enclosure for its bulk bag dischargers that contain spillage and dust that can escape through seams in the bag and folds in the spout.

The six-sided enclosure sits against the rim of a hopper or flange of downstream equipment and is equipped with an exhaust port for dust collection and a hinged door with inspection window.

The top of the enclosure contains a circular opening that allows passage of the bag spout to the equipment connection point. The flat bottom of the enclosure supports a Tele-Tube telescoping tube that pneumatically raises a Spout-Lock clamp ring which connects the clean side of the spout to the clean side of the equipment.

Allowing the telescoping tube to descend under its own weight maintains constant downward tension on the spout as the bag empties and elongates, as Flow-Flexer bag activators raise and lower opposite bottom edges of the bag at timed intervals to loosen compacted materials, promoting material flow and complete discharge from the bag.

The enclosure contains incidental leakage of fine powders from seams in the bag, as well as material released from bag spout folds during connection and disconnection activities. Associated dust is vented through the sidewall-mounted port to an optional Bag-Vac dust collector or plant bag house, preventing contamination of the environment.

For applications requiring retying of partially empty bags, an optional Power-Cincher pneumatically-actuated flow control valve cinches the spout concentrically on a horizontal axis for easy tie offs, and vertically in a tight zigzag pattern to prevent leakage of powders.

Constructed of stainless steel finished to food, pharmaceutical and industrial standards, the dust containment enclosure is offered on all Flexicon dischargers including models requiring forklift loading of bulk bags, models that load bags using an electric hoist and trolley, half-frame dischargers that require a forklift or plant hoist, and split-frame dischargers for forklift loading of bags in low headroom areas. 

All can be integrated with the company's mechanical, pneumatic and tubular cable/disc conveyor systems, and are available with controls for automated weigh batching directly from bulk bags.

IBC benefits

With manufacturing centres in both Europe and North America, Greif supplies IBCs to many process industries, including pharmaceuticals, food, lubricants and chemicals. The company says that its intermediate IBCs are an efficient container for large product quantities and that they decrease customer costs through reduced handling, storage space and shipping expenses. “IBCs are easy to use, transport and recycle – and come with a complete care management service,” notes the company.

The company’s standard IBC includes a high-density polyethylene bottle in a solid or tubular reinforced steel cage that is attached to a pallet. Pallet options vary from wood, steel, plastic or hybrid.

Its latest offering is the Big Drum IBC. This, says Greif, offers sizable advantages over standard fibre drums for shippers of non-regulated dry or liquid materials, including bulk wire, resins, paints, chemicals, food and beverage products, and more. Available for dry, as well as with liners and bottles for liquids, Big Drum can be readily customised.

With up to a 330 gallon capacity, 44” diameter and 60” height, the IBC can hold as much as six 55-gallon drums, reducing handling, filling and shipping requirements; it weighs less and costs less too.

The tough, durable 100% fibre drum is made from recycled linerboard drum stock, sturdy enough to stack three high. Both Big Drum models withstand up to 20,000 lbs. of compression, eliminating the need for additional strapping. Disposal is simple, too, via recycling or incineration. 

Bag filling efficiency key for peanut packer

US company Golden Grove sells the bulk of its 10,000 tonne peanut harvest in 900lb bulk bags that are shipped to customers around the world.

Originally company employees were manually filling 20 bulk bags per day. Three filling stations each contained a hopper fitted with a slide gate and a scale positioned below. An operator would open the slide gate, allowing the peanuts to fall into the bulk bag until the bag was within ±2 lb of the target 900lb weight. The process was extremely slow and labour intensive. Weighing accuracies could be improved to increase profitability as well.

The process also generated some spillage and possible product contamination. If the bag spout was not held firmly beneath the slide gate, peanuts fell on the floor and had to be swept up daily.  Operators were easily bored with the tedious process and would sometimes look at their cell phones during filling. On occasion cell phones (and other items) were dropped into the bulk bag contaminating the contents.

Golden Grove required a significantly faster contamination free process to meet the growing wholesale demand. The company turned to Spiroflow Systems who recommended an automated gain-in-weight filling system.

Golden Grove initially invested in a single Spiroflow C1-2 bulk bag filling system and the solution worked so well that it quickly purchased two more identical systems.  

As a result, the filling rate has increased to 300 bulk bags per day, weighing accuracy improved by over 400% and product spillage reduced.