Zinc sulfide flotation monitoring

PKL internship case study at PT. Generasi Muda Bersatu, analyzing ZnS concentrate recovery, reagent use, and process quality across the scavenging flotation unit.

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Froth Flotation
Scavenging Unit
Reagent Analysis
Technical Reporting

Internship context

This PKL was completed at PT. Generasi Muda Bersatu in Kampung Cihaur, Simpenan, Sukabumi, from 11 January to 11 February 2022. The work focused on zinc sulfide concentrate processing from sphalerite-bearing ore using froth flotation.

The report connected chemistry knowledge with plant observation: how reagent selection, slurry conditioning, particle size, and scavenging flotation affect the recovery of ZnS concentrate.

What I monitored

I observed the production route from ore handling to concentrate storage, including crushing, grinding, classification, chemical conditioning, scavenging flotation, thickening, and vacuum filtration.

What I analyzed

I summarized 11 days of Zn recovery and reagent data, then used linear regression to evaluate how lime, copper sulfate, and xanthate related to recovered ZnS concentrate percentage.

Field documentation

Photos from plant observation and report documentation

Selected photos from the PKL report show the real operating environment: grinding equipment, scavenging flotation, reagent storage, ore feed, concentrate filtration, and product storage.

Ball mill unit used in zinc sulfide concentrate processing — GrindingBall mill unitOre was ground into fine slurry before classification and flotation.

GrindingBall mill unitOre was ground into fine slurry before classification and flotation.

Scavenging flotation unit at PT Generasi Muda Bersatu — ScavengingFlotation lineThe scavenging unit recovered ZnS particles that were not floated in earlier stages.

ScavengingFlotation lineThe scavenging unit recovered ZnS particles that were not floated in earlier stages.

Sodium butyl xanthate reagent drum used in flotation — ReagentXanthate collectorSodium butyl xanthate supported attachment between activated mineral surface and froth.

ReagentXanthate collectorSodium butyl xanthate supported attachment between activated mineral surface and froth.

Ore getting sandy material observed during internship — Ore feedOre getting sandyDifferent ore forms were observed before entering the processing route.

Ore feedOre getting sandyDifferent ore forms were observed before entering the processing route.

Filtered zinc sulfide concentrate being packed into jumbo bags — ProductFiltered concentrateRecovered concentrate was dewatered before being packed into jumbo bags.

ProductFiltered concentrateRecovered concentrate was dewatered before being packed into jumbo bags.

Warehouse storage for packed zinc sulfide concentrate — StorageConcentrate warehousePacked concentrate was stored after filtration and moisture reduction.

StorageConcentrate warehousePacked concentrate was stored after filtration and moisture reduction.

Process understanding

From raw ore to stored ZnS concentrate

The portfolio version of this PKL highlights the practical flow: ore is reduced in size, converted into slurry, conditioned with reagents, recovered by froth flotation, then dewatered and packed.

Ore preparation

Massive ore was reduced from around 25 cm to 5 cm by jaw crusher, then to 1-2 cm by cone crusher.

Grinding and classification

Ball mill and screw classifier prepared slurry at roughly 150-200 mesh before chemical conditioning.

Reagent conditioning

Lime, copper sulfate, sodium butyl xanthate, sodium metasilicate, and pine oil were used to control flotation behavior.

Scavenging flotation

The scavenging unit recovered remaining sphalerite by making ZnS hydrophobic and carrying it with froth.

Dewatering and storage

Recovered concentrate was settled in a thickener, filtered, packed in 1000 kg jumbo bags, and stored.

Reagent chemistry

Reading flotation performance through reagent roles

The strongest part of the report is the link between chemical function and operational outcome. Copper sulfate activates the sphalerite surface, xanthate collects the activated mineral, pine oil creates froth, lime controls pH, and sodium metasilicate suppresses pyrite.

pH regulator

Lime

Controlled slurry alkalinity so flotation could happen in the right operating window.

Activator

Copper sulfate pentahydrate

Formed a copper sulfide layer on sphalerite surface so xanthate could attach more effectively.

Collector

Sodium butyl xanthate

Helped make activated ZnS particles hydrophobic so they could rise with froth.

Pyrite depressant

Sodium metasilicate

Reduced pyrite interference by supporting gangue depression during flotation.

Frother

Pine oil

Produced and stabilized bubbles that carried hydrophobic mineral particles to the surface.

Analysis outcome

The report evaluated 11 days of production data from 15 to 25 January 2022. Linear regression showed R2 values above 0.84 for lime, copper sulfate, and xanthate, indicating that reagent use had a meaningful relationship with recovered ZnS concentrate.

11 daysdaily recovery and reagent data

R2 0.863lime relation to Zn recovery

R2 0.852copper sulfate relation to Zn recovery

R2 0.846xanthate relation to Zn recovery

Linear regression summary from 15-25 January 2022 production data
Chemical variable	Function	R2 value	Portfolio reading
Lime	pH regulator	0.86337082	Strongest relationship in the report; pH control was closely related to Zn recovery.
Copper sulfate	Activator	0.851697157	Activation of sphalerite surface showed a meaningful relationship with recovery output.
Sodium butyl xanthate	Collector	0.846196148	Collector usage also showed a meaningful relationship with recovered ZnS concentrate.

The PKL report interpreted values above 0.6 as evidence that reagent addition influenced ZnS concentrate recovery in the scavenging unit.

Daily zinc recovery graph from PKL report — Recovery trendDaily Zn recoveryRecovery data from 15 to 25 January 2022 was used to read process variation.

Recovery trendDaily Zn recoveryRecovery data from 15 to 25 January 2022 was used to read process variation.

Daily reagent usage graph from PKL report — Reagent trendChemical usageLime, copper sulfate, and xanthate usage were compared against recovery behavior.

Reagent trendChemical usageLime, copper sulfate, and xanthate usage were compared against recovery behavior.

This experience strengthened my ability to observe plant operations, connect chemical mechanisms with process output, and turn technical data into clear reporting for QA/QC, laboratory, and production-support roles.

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