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Lead recovery from metallurgical slag by flotation

Lead recovery from metallurgical slag by flotation. Paulo F. A. Braga, João A. Sampaio , Carlos A. M. Baltar , Arnolfo M. Coelho, João A. F. Nunes. Introduction.

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Lead recovery from metallurgical slag by flotation

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  1. Lead recovery from metallurgical slag by flotation • Paulo F. A. Braga, João A. Sampaio, Carlos A. M. Baltar, Arnolfo M. Coelho, João A. F. Nunes

  2. Introduction • Brazil does not have a primary production of refined metallic lead. The whole production is based upon the recycling of automotive, industrial and telecommunication batteries. • In 2010 the battery recycling industry produced 115,000 t of metallic lead from 2nd production. • Moura is the largest recycler/ manufacturer of batteries in Brazil (7.106units/y).

  3. Introduction • Operated at 90% efficiency (the ratio of the number of recycled batteries and the number of new batteries produced). • With the increase in price of metallic commodities such as lead, several studies were carried out, aiming to: • minimize the loss of this metal in the industrial processes or; • for an additional recovery of the lead from metallic slags.

  4. introduction • Recycling process starts with the removal of metallic parts such as connectors and screws and subsequently with the reduction of the battery scrap and separation of the plastic casing from the lead grates and lead paste. • Lead paste follows the process of separation, casting, refining and manufacturing of new batteries. • Plastic is recovered and reused in the production of casing and cover for the new batteries. • Acid solution is neutralized by lime or limestone.

  5. Introduction 32% Pb 3% PbO 17% PbO2 36% PbSO4 • A typical automotive battery scrap contains: • The main reactions of the metallurgical processes are: • 2PbSO4 + Na2CO3 + Fe + 9C → 2Pb + FeS.Na2S + 9CO + CO2 (1) • PbO2 + C → CO + PbO (2) • 2PbO + C → CO2 +2Pb (3) • PbSO4 + 2C → PbS + 2CO2 (4)

  6. objective • The present research work aimed to study the flotation process on pilot scale for the recovery of lead from metallurgical slags rising from the recycling process of automotive batteries. • There were also several tests carried out in gravity concentration equipment with the purpose of assessing this process route for the recovery of lead concentrate.

  7. Methodology Chemical analysis of the slag sample: X-ray diffraction (XRD): metalic lead, magnetite (Fe3O4), hatrurite (Ca3SiO5), galena (PbS); jamesonite(Pb4FeSb6S14) and cotunnite (PbCl2).

  8. methodology Screen size distribution and lead grade per size fraction.

  9. methodology Flotation Circuit Equipments: • jaw crushers • vibrating screen • conditioners • reagent feeder • flotation cells type Denver nº 7 Sub-A • Wilfley laboratory concentrating table • Humphreys spiral concentrator • crossflow 2x4 . Meteringpumps Flotation Cells Reagents: potassium amyl xanthate ( PAX) – collector; methyl isobutyl carbinol (MIBC) - frother; sulphuric acid (H2SO4) - pH adjuster.

  10. methods Slagof lead (25 t) Jawcrusher (1”) Sample Preparation Screening (2 mm) Jawcrusher (1/2”) Screening (2 mm) Hammermill (5 mm) Screening (2 mm) Discard (+ 0,7 mm) Screening (-0,7 mm) Homogenization pile

  11. collector: potassium amyl xantate feed tank frother: MIBC conditioner tank flotation cell rougher dosage pump Bomba Concentrate Tailings pump methods Reagent system and operating conditions in laboratory scale for flotation tests were previously defined by Baltar (2005). • Flotation Procedure Slag : 105 - 37 µm (size); pH: 8 (sulphuric acid); 50 kg/h: slag (flow rate); 150 g/t: PAX (collector); 50 g/t: MIBC (frother).

  12. results Flotation test

  13. results • Wilfley laboratory shaking table test

  14. results • Crossflow hydraulic classifier test (elutriation test) • Spiral concentrator test

  15. FINAL REMARKS • Main composition of lead metallurgical slag is: 16.9% PbO, 29.8% SO3 and 41.6% Fe2O3. • The main mineralogical species are: magnetite (Fe3O4); hatrurite (Ca3SiO5); galena (PbS); jamesonite (Pb4FeSb6S14); cotunnite (PbCl2) and metallic lead. • The fine fraction -37 m represented 51.9% of the bulk sample and contained 12.61% of lead.

  16. FINAL REMARKS • The flotation at pilot scale produced lead concentrates at 48.8% Pb and a concentration ratio of 2 and 80% recovery. These results were obtained after fine fraction removal (-37 μm); • Shaking table tests produced a concentrate at high grade, 55.9% Pb, and 37.2% recovery from the bulk sample; • Reprocessing the rougher flotation concentrate in the shaking table produced a final concentrate at 72.3% Pb, concentration ratio of 1.5 and 56.5% recovery.

  17. acknowledgments

  18. Thank You Muchas Gracias pbraga@cetem.gov.br

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