Mineral materials can behave very differently during packaging, storage and transport. Quartz sand, limestone granules, feldspar powder, kaolin and barite may require different FIBC configurations even when the target filling weight is the same.

Selecting a mineral FIBC should therefore involve more than checking its stated load capacity. Bulk density, particle size, moisture content, dust level and handling equipment should all be reviewed before the construction is finalized.

Start With Bulk Density

Material weight alone does not determine the required bag dimensions. At the same weight, a mineral with a lower bulk density occupies a larger volume.

The preliminary volume can be calculated as:

Required volume = filling weight ÷ material bulk density

A 90 × 90 × 90 cm FIBC has a theoretical geometric volume of approximately 0.729 m³. To place 1200 kg inside this volume, the material would require a bulk density of approximately 1646 kg/m³ or higher.

If the bulk density is only 1400 kg/m³, the same 1200 kg load requires approximately 0.857 m³. The bag may therefore need additional height, different base dimensions or a lower filling weight.

An FIBC is flexible and expands after filling. The calculation should be used for preliminary selection, followed by a representative filling trial with the actual mineral.

Match the Construction to the Particle Form

Dry minerals with relatively consistent granules can be evaluated with an uncoated FIBC after bulk density and filling conditions have been confirmed.

Fine materials such as kaolin, talc or ground feldspar create a different problem. Powder may escape through woven gaps or sewing needle holes, requiring coated fabric, a PE liner or sift-resistant seams.

Quartz sand, crushed ore and other hard particles may generate friction and local impact. Sharp-edged material should be tested in a representative bag to identify possible puncture or abnormal abrasion.

Fabric weight alone cannot prove suitability for sharp ore. A value such as 180 g/m² describes fabric mass per unit area and should be reviewed together with directional fabric strength, seam construction and complete-bag testing.

Consider Moisture During the Entire Transport Process

An uncoated FIBC can be considered for dry minerals that do not require a verified moisture barrier. It should not be described as waterproof or moisture-proof without test evidence.

A coated body, PE liner, closable top or external weather protection may be required where the mineral is hygroscopic, stored for an extended period or exposed to rain.

A mineral leaving the processing plant in a dry condition may still encounter outdoor handling, condensation inside the vehicle or a humid warehouse.

Buyers should therefore define both the material’s initial moisture content and the expected transport environment.

Match Loops, Top and Bottom to the Equipment

Loop quantity and effective length should match the actual lifting equipment. A four-loop FIBC is generally intended to have all designated loops engaged during lifting.

Unequal loop lengths, twisted webbing or incorrect forklift positioning may cause uneven loading. Burrs or sharp edges on the forklift tines can also cut or abrade the webbing.

The top construction should match the filling system. Open tops, duffle tops and filling spouts provide different levels of connection and dust control.

The bottom should be selected according to the discharge process. A discharge spout can be considered for controlled emptying, while other unloading methods require a suitable bottom and safe operating procedure.

Prepare a Usable Selection Brief

Before requesting a quotation, buyers should provide:

• Mineral name and downstream application;
• Target filling weight;
• Material bulk density;
• Minimum and maximum particle sizes;
• Dust content and permitted leakage level;
• Moisture content and hygroscopic behavior;
• Filling and discharge equipment dimensions;
• Forklift tine or lifting-hook dimensions;
• Indoor or outdoor storage conditions;
• Single-trip or repeat-use requirements.

For compatible dry ore granules, a reference configuration may include a 1200 kg specified capacity, 90 × 90 × 90 cm dimensions, 180 g/m² uncoated fabric and four side-seam lifting loops.

Minimum warp and weft strengths of 1600 N and a lifting-strap requirement of ≥18000 N can provide measurable component-level acceptance criteria.

These figures do not replace a complete-bag safety factor. A 5:1, 6:1 or UN claim requires the corresponding complete-bag tests and verifiable documentation.

FAQ

Why do minerals with the same weight require different FIBC sizes?

Different minerals have different bulk densities. A lower-density material occupies more volume at the same weight.

Calculate the theoretical volume first and then verify the proposed dimensions through a representative filling trial.

Can an uncoated FIBC package mineral powder?

That depends on particle size and the permitted leakage level. Fine powder may escape through woven gaps or sewing needle holes.

A coating, PE liner or sift-resistant seams may be required.

Does heavier fabric automatically make a mineral FIBC more reliable?

No. Fabric weight, warp and weft strength, seams, lifting loops and complete-bag test results must be considered together.

Any reliability claim should be supported by measurable material and test data.

Is the specified load capacity the same as the safe working load?

Not automatically. Specified capacity is one product parameter, while a safe working load and safety factor require the appropriate complete-bag test evidence.