By Senjie Filter Press Engineering Team · Last updated: 2026-09-10
Quick answer: A membrane filter press dewaters gold and copper concentrate to 8-12% moisture using 0.6-1.0 MPa feed pressure and 1.5-2.0 MPa membrane squeeze, versus 12-18% from a chamber press alone. PP monofilament cloth and automatic plate shifting are standard on concentrate circuits above roughly 20-30 tonnes/day.
Concentrate dewatering has a harder moisture target than most other filter press applications, because smelters and shipping contracts specify maximum transportable moisture limits. This guide covers the pressure, moisture target, cloth choice, and automation level typically specified for gold and copper concentrate filter presses.
What cake moisture should a concentrate filter press achieve?
A membrane filter press typically achieves 8-12% moisture on copper and gold concentrate, which meets most smelter intake specifications and IMSBC Code transportable moisture limit requirements for bulk shipping. A chamber filter press without membrane squeeze typically leaves concentrate at 12-18% moisture, which is workable for some domestic smelter deliveries but often too wet for export shipping without further treatment.
| Press type | Feed pressure | Squeeze pressure | Typical concentrate moisture | Typical cycle time |
|---|---|---|---|---|
| Chamber (no membrane) | 0.6-1.0 MPa | n/a | 12-18% | 1-3 hours |
| Membrane (manual) | 0.6-1.0 MPa | 1.5-2.0 MPa | 8-12% | 45-90 minutes |
| Fully automatic membrane | 0.6-1.0 MPa | 1.5-2.0 MPa | 8-12%, more consistent shot-to-shot | 30-70 minutes |
Why does moisture specification matter so much for concentrate?
Excess moisture in bulk concentrate cargo creates a liquefaction risk during sea transport, which is regulated under the International Maritime Solid Bulk Cargoes (IMSBC) Code’s transportable moisture limit (TML) requirements. Concentrate shipped above its TML can shift inside the hold, threatening vessel stability, so shippers and smelters require documented moisture testing and typically specify a working moisture ceiling below the regulatory limit as a safety margin.
Beyond safety compliance, many smelter offtake contracts include penalty clauses for concentrate delivered above a specified moisture percentage, since excess water adds shipping weight and processing cost at the smelter. Hitting 8-12% moisture consistently is therefore a commercial requirement, not just an engineering target.
What filter cloth works best for gold and copper concentrate?
PP (polypropylene) monofilament or multifilament filter press cloth is the standard choice for concentrate dewatering because it resists blinding from the very fine particle sizes typical of flotation concentrate (often below 75 microns) and releases cake cleanly during automatic plate shifting. PET (polyester) cloth is sometimes specified where higher tensile strength or resistance to specific process chemistry is needed, at a similar pore structure to PP.
- Monofilament PP: smooth surface, easy cake release, good for high-value concentrate where cloth cleanliness affects product purity.
- Multifilament PP: finer retention, useful for very fine concentrate particles, slightly harder to clean.
- Cloth life: typically 3-12 months depending on abrasion from the specific ore, closing pressure, and cycle frequency.
What plate size and pressure are typical for concentrate circuits?
Concentrate dewatering circuits commonly use 800-1500 mm plate membrane filter presses, sized to the concentrator’s daily concentrate production rather than raw ore throughput, since concentrate volume is a small fraction of processed ore. Feed pressure of 0.6-1.0 MPa during fill is standard, stepping up to 1.5-2.0 MPa membrane squeeze pressure for the final dewatering phase. Hydraulic closing pressure for the plate pack itself is typically 20-25 MPa to prevent cake leakage at the plate joints under squeeze pressure.
Is automation worth it for concentrate dewatering?
Automatic filter presses with PLC control, automatic plate shifting, and often automatic cloth washing are common on concentrate circuits above roughly 20-30 tonnes/day because they hold cycle time and moisture output more consistently shot-to-shot than manual operation, which matters when every shipment is tested against a contractual moisture specification. Automation also reduces operator handling of high-value concentrate, lowering both labor cost and product-loss risk from spillage during manual plate shifting.
Smaller operations or pilot-scale concentrate producers below this throughput often use manual or semi-automatic membrane presses, accepting slightly more operator involvement in exchange for lower capital cost.
What feed pump suits concentrate slurry?
Concentrate slurry is typically dense and abrasive, so a ceramic piston pump or heavy-duty slurry pump is generally preferred over lighter diaphragm pumps for continuous, higher-pressure feed to the press, particularly where feed density exceeds 50-60% solids by weight.
Why buy this from Senjie?
Senjie is a China-based manufacturer of filter presses, founded in 2014 and exporting to 40+ countries including major mining regions in Latin America, Africa, and Southeast Asia. Senjie builds membrane and fully automatic filter presses purpose-configured for concentrate dewatering, sized from 800 mm to 2000 mm plates, together with abrasion-resistant filter cloth and slurry feed pumps matched to concentrate density.
Frequently Asked Questions
What moisture level does a filter press achieve on copper concentrate?
A membrane filter press with 1.5-2.0 MPa squeeze pressure typically achieves 8-12% moisture on copper concentrate, meeting most smelter and shipping specifications, versus 12-18% moisture from a chamber press without membrane squeeze.
What filter cloth is best for gold and copper concentrate?
Monofilament or multifilament polypropylene (PP) cloth is the standard choice for gold and copper concentrate because it resists blinding from fine particles and is easy to discharge cleanly; polyester (PET) cloth is sometimes used where higher mechanical strength is needed at similar pore structure.
Why is cake moisture below 12% important for concentrate shipping?
Many concentrate shipping and smelter contracts specify a maximum transportable moisture limit to prevent liquefaction risk during sea transport under the IMSBC Code, and to avoid smelter penalty clauses for excess moisture, making the 8-12% target a common commercial requirement rather than just a technical preference.
Does concentrate dewatering need an automatic filter press?
Not always, but automatic filter presses with PLC control and automatic plate shifting are common on higher-throughput concentrate circuits (typically above 20-30 tonnes/day) because consistent cycle times help hold moisture specification tightly and reduce operator handling of high-value material.
What feed pressure does a membrane press use for concentrate?
A membrane filter press for gold or copper concentrate typically operates at 0.6-1.0 MPa feed pressure during the fill phase, followed by 1.5-2.0 MPa membrane squeeze pressure to push final moisture down toward the 8-12% target.
Need a moisture-target specification for your concentrate? Contact Senjie’s engineering team for a configuration recommendation.