Processing of Ni-Laterite Bacterial Leach Liquor for Recovery of Zn, Mn, Co and Ni Using Solvent Extraction Institute of Minerals and Materials Technology (CSIR) Bhubaneswar , Odisha, India By K.C. Nathsarma

Hydro & Electrometallurgy Department: Mission & Goal To assist public / private sector organizations / industries in developing processes for extraction of metals from: Ores and concentrates. Lean, complex, off-grade ores and minerals. wastes generated by metallurgical & allied industries (tailings, residues, sludges and effluents).

Role of the Department To develop processes and products. Exploit primary and secondary resources. Employ hydro- & electro-metallurgical routes. Prepare feasibility reports. Develop basic and detailed engineering process packages. Assist in environment pollution abatement.

Atmospheric & Pressure Leaching Batch Autoclaves (300 ml – 1400 L) Batch Autoclaves (300 ml – 1400 L) Continuous Autoclaves (500 LPH) Continuous Autoclaves (500 LPH) Stirred Tank Reactors (0.5 kL – 1 kL) Stirred Tank Reactors (0.5 kL – 1 kL) 1400 L Autoclave for Pressure Leaching 1400 L Autoclave for Pressure Leaching 1400 L Autoclave for Pressure Leaching

Thickeners Thickeners Filters (Vertical leaf, Candle, Chamber) Filters (Vertical leaf, Candle, Chamber) CCD Units CCD Units 1 ton Filter Press 1 ton Filter Press 1 ton Filter Press Solid-Liquid Separation

Mixer Settlers Mixer Settlers 26 Stages 200 L/h aqueous SX Unit. 26 Stages 200 L/h aqueous SX Unit. 26 Stages 200 L/h Aqueous SX Unit Solvent Extraction

Electrowinning Rectifiers and Potentiostat Rectifiers and Potentiostat Charge- Discharge Unit Charge- Discharge Unit 100 kg/day electrowinning Unit 100 kg/day electrowinning Unit 100 Kg/day metal Electrowinning Cells

Supported liquid membrane (6 L/h) Supported liquid membrane (6 L/h) Reverse Osmosis, Nano- filtration & Ultra-filtration membrane integral system (1 kL/h) Reverse Osmosis, Nano- filtration & Ultra-filtration membrane integral system (1 kL/h) Membrane Technology

M/s Rubamin Pvt. Ltd. 100 tpy plant was set up for recovery of cobalt from scrap/sludge M/s Shalina Corporation Ltd. 135 tpy plant was set up for cobalt carbonate M/s S.K. Enterprises & M/s Pantnagar Fertilizers Copper and zinc from spent catalyst at 250 kg per day Nickel Technology Proving Plant Major Achievements

Recovery of Nickel by Solvent Extraction

One ton Nickel bioleaching of Chromite Overburden, Sukinda Bacterial Generation TankNickel cathode after electrowinning. Activation of COB in Rotary Kiln Nickel Bioleaching Pilot Plant at IMMT, Bhubaneswar (10 ton)

Process Flowsheet

Composition of the Ni-Laterite Bacterial Leach Liquor Metal IonConcentration, kg/m 3 Manganese Nickel Cobalt Zinc Aluminium Iron3.719 Chromium pH1.27

pH % Fe pptd. %Ni pptd. %Co pptd. %Cr pptd. %Al pptd. %Mn, pptd. %Zn pptd Precipitation of metal ions from Ni-laterite leach liquor using CaCO3

Precipitation of Fe, Al and Cr from the Ni-laterite bacterial leach liquor with CaCO 3

Chemical reactions

Main findings The Ni-laterite bacterial leach liquor was processed for metal separation. Treatment with CaCO 3 at pH 4.4 precipitated 100% Fe, 96.98% Al, and 70.42% Cr. The remaining Al and Cr was precipitated at pH 5.4 using 50% NH 3 solution leading to quantitative precipitation of Al and Cr with minor losses of Ni, Co and Mn. Extraction of all the metal ions increased with increasing equilibrium pH and extractant concentration. Stripping of all the Metal-LO was carried out with H 2 SO 4.

Extraction of Zn

Effect of equilibrium pH on extraction of Zn with 0.1M TOPS-99

Plot of Log D Zn vs. equilibrium pH

Effect of [TOPS-99] on extraction of Zn

Plot of LogD Zn vs. Log [TOPS-99]

McCabe-Thiele plot for extraction of Zn with 0.1M TOPS-99

Stripping of Zn-LO with H 2 SO 4

McCabe-Thiele plot for stripping of Zn-LO with 15 kg/m 3 H 2 SO 4

Main findings Extraction of Zn It was carried out with 0.1M TOPS-99 in 3-stages at O:A ratio of 1:4. The Zn-LO contained kg/m 3 Zn leading to 97.9% extraction. Stripping of Zn-LO was carried out with 15 kg/m 3 H 2 SO 4 in 2-stages at O: A ratio of 9:2.

Extraction of Mn

Extraction of Mn (contd.)

Main findings Extraction of Mn It was carried out with 0.04M NaTOPS-99 in 2- stages at 1:1 phase ratio. The LO contained kg/m 3 Mn leading to 93.34% extraction. The Mn-LO was stripped with 15 kg/m 3 H 2 SO 4 in 2-stages at O:A ratio of 9:1. The strip solution contained kg/m 3 Mn.

Effect of equilibrium pH on extraction of cobalt with M NaCyanex 272

Plot of Log D Co vs. equilibrium pH.

Effect of [Extractant] on extraction of cobalt

Plot of Log D Co Vs. Log[Cyanex 272]

McCabe-Thiele plot for extraction of cobalt using M Cyanex 272

Scrubbing off Ni from the Co-LO with CoSO 4 solution at 1:1 phase ratio.

Scrubbing off Ni from Co-LO with CoSO 4 solution at O:A =10:1

Scrubbing off Ni from the Co-LO with 7.5 kg/m 3 CoSO 4 at different O:A ratios

Stripping of Co-LO with H 2 SO 4.

McCabe-Thiele plot for stripping of Co-LO with 60 kg/m 3 H 2 SO 4

Stripping of Co-LO with oxalic acid

McCabe-Thiele plot for stripping of Co-LO with 1.5 N oxalic acid

Main findings Extraction of cobalt It was carried out with M Cyanex 272 in 3-stages at 1:1 phase ratio. The LO contained kg/m 3 Co and kg/m 3 Ni. The scrubbing off Co-LO with 12.5 kg/m 3 CoSO 4 solution at O:A ratio of 10:1 expelled 0.02 kg/m 3 Ni. The 0.75 kg/m 3 Co-LO was stripped to 94.5% with 60 kg/m 3 H 2 SO 4 in 2-stages at O:A ratio of 10:1. The Co-LO was also stripped with 1.5 N oxalic acid in 2- stages at O:A ratio of 4:1. The stripping was 97.16%.

Extraction of Ni

Effect of equilibrium pH on extraction of Ni & Plot of Log D Ni Vs. equilibrium pH

Effect of [Extractant] on extraction of Ni & Plot of Log D Ni Vs. Log[Extractant]

McCabe-Thiele plot for extraction of Ni with 0.12M NaD2EHPA & Stripping of Ni-LO

COB leach liquor (pH 1.84) Precipitation with CaCO 3 (pH 4.4) Precipitation with NH 4 OH (pH 5.4) SX of Zn SX of Mn SX of Co SX of Ni Stripping with H 2 SO 4 Stripping with H 2 SO 4 Stripping with H 2 SO 4 0.1M TOPS-99 ZnSO 4 MnSO 4 CoSO 4 NiSO 4 Filtrate 0.04M NaTOPS M Na Cyanex M NaTOPS-99 Filtrate A Conceptual Flow sheet for Processing of Overburden Leach Liquor to recover of Zn, Mn, Co and Ni values.

Other Relevant activities Treatment of complex sulphide Copper converter slag Recovery of metal values from cobalt cake (Cu, Ni, Co, Zn by SX) Nickel extraction Polymetallic nodule Solvent extraction of uranium from phosphoric acid

Pilot Plant at Udaipur Ni-Co SX Section Mining site ~2000 km from the nearest Indian Port Nodule distribution : 7-10 kg/m 2 Metallurgy of Deep-sea Manganese Nodule of Indian Ocean

Bioheap Leaching at HCL, Malanjkhand

Bioleaching and SX-EW flow sheet HCL

Source: HWP Talcher Continuous processing of Phosphoric acid at 3 L/h Continuous campaign: Four weeks Design data being generated for 6 stages extraction, 2 stage scrubbing and 6 stage stripping for 10,000 L/h plant Solvent Extraction of Uranium

CONCLUSIONS The Ni-laterite bacterial leach liquor was processed for metal separation. The extraction sequence: Precipitation -> Zn -> Mn -> Co NaD2EHPA was used for extraction and H 2 SO 4 was used for stripping Nickel extraction was carried out with 0.12 M NaTOPS-99 in 2-stages at O:A ratio of 2:3. The LO contained kg/m 3 Ni. The Ni-LO was stripped to 89% with 20 kg/m 3 H 2 SO 4 in 2-stages at O: A ratio of 8:1.