FLS Knelson and gravity gold recovery: circuit design notes for plant engineers
Reviewed by Joe Ashwell
First reported on International Mining – News
30 Second Briefing
FLS product manager Chris Arnold says high gold prices are driving miners to maximise gravity-recoverable gold (GRG) using Knelson Concentrators in mill circuits rather than relying solely on cyanide leaching. Plants that previously treated only a small bleed of the mill circulating load are now considering full-stream or multiple Knelson installations, targeting GRG often above 50–70% of total gold in suitable ores. The shift demands tighter cyclone control, upgraded pump capacity and careful integration of intensive leach reactors for the Knelson concentrate.
Technical Brief
- Knelson Concentrators use high-g centrifugal fields to separate dense GRG from mill discharge slurry.
- Units operate as fluidised-bed concentrators, with water injection maintaining bed stratification and minimising blinding.
- Concentrate is periodically or continuously discharged as a high-grade, low-mass stream for intensive leaching.
- Cyclone underflow is typically the preferred Knelson feed, exploiting coarser, denser particle residence.
- Circuit layouts often include dedicated gravity-recovery pump boxes and bypass lines for maintenance flexibility.
- GRG testing is used to quantify gravity-recoverable fractions before design.
- Knelson installations are commonly retrofitted into existing mills with minimal footprint, using modular skid-mounted packages.
- For brownfields, gravity circuit upgrades offer relatively low capital intensity compared with new leach or flotation capacity.
Our Take
FLS’s focus on Knelson gravity gold recovery sits alongside a broader push into high-value processing equipment in our database, with recent pieces covering its semi-mobile crushing station at Vale’s S11D iron ore mine and a major comminution package for a South American copper concentrator.
The current article is one of relatively few gold-specific items within our mining coverage compared with iron ore and copper, suggesting FLS is using the high gold price environment to rebalance its portfolio messaging toward precious metals as well as bulk and base commodities.
With FLS’s new CEO, Toni Laaksonen, coming from the service business line, the emphasis on Knelson concentrators for gold likely aligns with a strategy to grow aftermarket and optimisation services around installed gravity circuits rather than just one-off equipment sales.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
Related Articles
Related Industries & Products
Mining
Geotechnical software solutions for mining operations including CMRR analysis, hydrogeological testing, and data management.
CMRR-io
Streamline coal mine roof stability assessments with our cloud-based CMRR software featuring automated calculations, multi-scenario analysis, and collaborative workflows.
HYDROGEO-io
Comprehensive hydrogeological testing platform for managing, analysing, and reporting on packer tests, lugeon values, and hydraulic conductivity assessments.
GEODB-io
Centralised geotechnical data management solution for storing, accessing, and analysing all your site investigation and material testing data.