Lithium carbonate is commonly supplied in powder form. Particle size, bulk density and flowability may vary between grades. Finer material generally places higher demands on fabric openings, needle holes and filling connections.

Powder escape does not necessarily mean that the body fabric lacks tensile strength. Even when the fabric meets its specified strength requirement, fine material may still escape through:

• Openings in the woven fabric
• Needle holes created by stitching
• Connections between the top panel and body
• Connections between the body and bottom panel
• Filling-spout seams
• Baffle attachment seams
• Gaps between the filling machine and spout

A Lithium Carbonate FIBC Bag should therefore be evaluated according to its coating, seam treatment, liner and equipment connection—not only its fabric weight.

Coated Fabric Controls Woven Openings

FIBC fabric is formed by interwoven tapes, leaving small openings in the woven structure. Fine lithium carbonate may pass through these openings during filling impact, air displacement or transportation vibration.

A coating adds a continuous layer over the fabric surface and reduces the number of exposed woven openings. The existing bag uses 190 g/m² internally coated body fabric, while the top and bottom panels use 185 g/m² internally coated fabric.

Coating mainly addresses the fabric surface. It does not automatically close needle holes created during sewing. A coated FIBC should therefore not automatically be described as completely leak-proof.

Why Do Seams and Needle Holes Require Separate Treatment?

An FIBC must be assembled by sewing together its body, top, bottom, spouts and internal baffles. Sewing needles create holes in the fabric, while component connections may form additional powder-escape paths.

The documented lithium carbonate bag uses several seam treatments:

• Double-folded filling- and discharge-spout seams
• Double-fold, single-stitch connection between the top panel and body
• Double-fold, double-stitch connection between the body and bottom panel
• Double-sided cotton tape at the top and bottom connections
• Single-sided cotton tape along the baffle connections
• Stitch density of 10 stitches per 10 cm

Folded edges reduce direct exposure of the cut fabric edges, while cotton tape supports powder control at specified seams. Actual performance still depends on particle size, thread tension and filling pressure.

The Filling Connection Is Often Overlooked

Even with suitable coated fabric and seam construction, powder may escape if the filling-machine outlet does not match the filling spout.

The existing bag has a nominal Φ45 × 60 cm filling spout. Before operation, confirm:

• Filling-machine outlet diameter
• Spout insertion depth
• Position of the tie or clamping device
• Filling speed
• Air-displacement path
• Dust-collection connection

Powder entering the bag displaces the air already inside it. If filling is too fast and the air cannot escape properly, dust-laden air may leave through the spout connection or stitched areas.

What Do Coating, Seam Tape and Liners Control?

Coated fabric and treated seams may be sufficient for general powder control. A separate PE liner should be evaluated for finer powder or applications with stricter cleanliness or moisture requirements.

Fabric Strength Is Not the Same as Powder Control

The existing body fabric has a specified tensile strength of ≥1,700 N/50 mm and a weaving density of 54 × 54 yarns per 10 cm. These parameters describe the material structure and tensile performance.

Powder control depends more directly on:

• Whether the woven openings are covered
• Coating continuity
• Needle-hole treatment
• Open or incomplete seams
• Liner integrity
• Filling-equipment connection

A fabric weight of 190 g/m² or tensile strength of 1,700 N/50 mm alone cannot determine whether the bag is suitable for a specific lithium carbonate particle size.

How Can Powder Control Be Verified Before Production?

1. Fill a sample bag with the actual material

Lithium carbonate grades can differ in particle size and flowability. Testing with the customer’s actual powder can reveal issues that are not visible during an empty-bag inspection.

2. Inspect critical connection areas

After filling, inspect:

• All body surfaces
• Top-panel seams
• Bottom-panel seams
• Filling-spout attachment
• Discharge-spout attachment
• Baffle seams
• Areas around the lifting-loop attachments

3. Simulate normal handling

Lift, position and transfer the filled sample according to the intended operating process. Check whether vibration or bag deformation creates new powder-escape points.

4. Document the acceptance conditions

The order specification should define:

• Lithium carbonate grade used for testing
• Particle-size range
• Filling weight
• Liner configuration
• Permitted powder condition
• Inspection positions and methods
• Sample and production acceptance criteria

Conclusion

Reducing powder escape during lithium carbonate filling requires control of woven openings, sewing needle holes, component connections and the filling-machine interface.

Coated fabric can reduce the risk of powder passing through woven openings. Folded seams and sealing tape support specified connection areas, while separate liners and dust-control equipment may be required for stricter powder or moisture-control applications.

The final bag configuration should be based on the actual particle size, filling speed, equipment interface and acceptance criteria, followed by a sample filling test.