QINFENG Custom FIBC manufacturer since 2001
Construction & Building Materials Application brief
A mineral processor bagging dried silica sand into 1.0-1.5 t lots must keep every bag inside the crane and fork-truck limit while the sand stays dry and free-flowing through a sea leg and empties without leaving a heel.
Plant managers and procurement leads at silica sand quarries, drying and screening plants, and mineral traders that re-bag for export. They supply glass batch plants, foundries and filtration media producers in Europe, the Gulf and Southeast Asia. Material is dried silica sand at roughly 1.2-1.6 t/m3 loose bulk density, typically graded 0-1 mm or 0.1-0.6 mm, bagged after a fluid-bed or rotary dryer.
Silica Sand and other dry bulk solids, typically 0.8–1.6 t/m³.
Handling chain
Filling runs on a gravity or air-assisted spout at 20-40 bags per hour. Fill weight is the control point, because sand does not settle after closing, so any overfill translates directly into a crane overload. Lifting is by single-loop or four-loop crane with a spreader beam, and sometimes by fork truck with a bag lifter. Storage is typically 4-8 weeks, part of it on an open quay, so the bag sees direct sun and rain before loading. Discharge is by bottom spout over a hopper or by cutting the base; dry free-flowing sand empties in seconds once the neck is open, so neck diameter and tie-off method decide how much sand is left behind.
Filled on automated spouts or semi-manual toll lines. High-speed de-aeration shapes the square footprint before the bag leaves the fill station.
Stacked two to three tiers high in transit warehouses. A baffle construction that does not bulge keeps the stack square instead of leaning into the aisle.
Lifted three to five separate times by port stevedores. Reinforced loop anchoring and cross-corner loops resist fork abrasion and tine punctures.
Has to fit inside the container wall, at roughly 2,350 mm internal width. A square footprint uses the cube without the bag dragging on the wall.
What fails in this chain
Overload: dried sand holds its fill volume, so a 1.5 t fill in a bag rated 1.25 t SWL is a real failure mode; fill weight is checked per bag on a scale and the SWL is matched to the crane's working load. Leakage: fine 0-1 mm sand escapes through any stitch line that is not sealed, so the leak path is the seam and the spout closure rather than the fabric body. Moisture: the sand is sold against a dryer specification, so the liner and fill-port closure protect the sale value, not only the bag. Abrasion: sharp quartz grains work on the fabric at the fill spout and in the bottom corners under road vibration; coated fabric and reinforced corner panels are the usual control. Puncture: pallet nails, loader buckets and rebar on the quay are the common sources, controlled by handling rules and by keeping the bag on a pallet or slip sheet.
Hazard: A standard tubular bag rounds out as it fills, wasting container volume and leaning in a warehouse stack.
QINFENG defense: Internal perforated ultrasonic baffles hold a square profile after fill, which is what makes three-high stacking in a shed predictable.
Hazard: Repeated lifting by rough tines tears side seams or frays loop attachment bases at transhipment hubs.
QINFENG defense: Heavier coated fabric with reinforced corner perimeter wraps and extra loop reinforcement backing, specified from the number of relifts.
Hazard: Faded printing or a torn document pouch causes customs delays and rejected cargo at the destination port.
QINFENG defense: Flexographic printing with UV-cured inks and a reinforced document pocket sewn onto the body seam, agreed before production.
Hazard: Unsheltered storage while awaiting vessel arrival degrades untreated polypropylene yarn within weeks.
QINFENG defense: UV-stabilised masterbatch in the tape, selected for how long the consignment actually waits on the quay rather than for the total storage period.
What we would quote
For dry free-flowing sand the real choices are coated versus uncoated fabric and whether a separate liner is needed. Coated fabric suits 0-1 mm grades and humid or outdoor storage; uncoated fabric is workable for coarser graded sand stored under cover, but expect dust at the seams. A four-loop bag with a discharge spout suits plants that have a hopper, while a single-loop or duffel-top bag suits sites that cut the bag open. Liner choice follows the moisture specification and the length of the sea leg, not the bag size.
Before we can quote
Bag dimensions, baffle spacing and the safety margin all follow from these. Answer the ones you can and leave the rest; the missing details can be settled with our engineers.
Loose, not tapped. Dried silica sand commonly runs 1.2-1.6 t/m3; this sets the fill volume for a given weight.
A graded 0-1 mm sand behaves differently at the spout and the seams from a fine 0.1-0.6 mm filtration grade.
Sand is normally bagged at or below the dryer target; anything above it changes the liner decision.
Confirmed per project: crane or fork-truck rating, spreader beam, and the site's own lift limit.
Bottom spout over a hopper, duffel top, or cut open on the ground; this decides the neck diameter.
Outdoor quay storage drives the UV and moisture decisions; a typical export leg is 4-8 weeks.
This page covers bagging of dried, graded silica sand in 500-1500 kg lots. It does not cover wet or unclassified quarry sand, sand above the dryer's moisture target, or pneumatic transfer systems. Fill weight, fabric weight, liner type, spout diameter and lifting method are confirmed per project. No certification, food-contact approval or third-party test result is claimed, and any third-party testing is arranged on request and quoted separately.
Talk to the applications team
We will come back with the construction we would build, the safety factor it carries and the dimensions that fit your loading plan — with drawings and a prototype before any bulk run.