role of test work in process engineering2013)_testwork_in_process_engine… · case study tailings...

Orway Mineral Consultants (WA) Pty Ltd

Role of Test Work in Process Engineering


Overview

Test Work and Project Development Stages

Ore Preparation Test Work

Leach Test Work

Case Study

Tailings – Geochemistry

Radionuclide Considerations



Stage of development % Estimate Accuracy Test work guidance

Proof of concept +/- 50 - Single batch leach test

Concept +30, -15 - Batch tests on extraction

Pre-feasibility +25, -15 -Comminution test work

- Batch and lock cycle test work

Feasibility +15, -10

-Variability test work

- Pilot plant

- Vendor equipment test work

- Geotechnical and geochemical test work

Test work requirements vary

according to:

Process risk areas

Environmental regulation

Financing requirements

Internal requirements


Overview



Leach Test Work

Case Study





a) Gyratory Crusher

b) SAG Mill

A complete comminution characterization requires approximately 200

kg of sample in the form of either rock chips or PQ core (85 mm

diameter)



Parameter Unit Value

- Abrasion index (Ai) 0.142

- Crush work index (CWi) kWh/t 15.0

- Bond rod work index (RWi) kWh/t 22.5

- Bond ball work index (BWi) kWh/t 14.7

- SAG mill comminution (SMC) – parameter A*b 29.0

- SAG mill comminution (SMC) – parameter ta 0.27

- Ore SG 2.65

Criteria Units

Primary Crusher

Crusher Type Jaw

Model Sandvik CJ615

Installed Motor kW 200

Secondary Crusher

Crusher Type Cone

Model Sandvik CH660 EC


SAG Mill

Diameter – Inside

Shell m

8.53

EGL m 4.80

Motor Power MW 6.5

Recycle Crusher

Crusher Type Cone

Model Sandvik CH440 MF


1) Ore comminution characteristics

from test work

2) Specific energy

calculations

3) Equipment selection

Database information

Simulation models


Overview



Leach Test Work

Case Study




Leach Test Work

Leach:

Acid

Alkaline

Heap leach

In-situ leach

Tank leach

Pressure leach


Leach Test Work

Acid leach

Insoluble tetravalent uranium requires oxidation to the hexavalent state;

this is done via ferric iron:

Alkaline leach

Carbonate leach of hexavalent uranium (e.g. Carnotite)

Any tetravalent uranium present requires an oxidant: oxygen, air or

hydrogen peroxide


Leach Test Work

Mainly used in acid leach; some

application on alkaline leach

Used for low grade ores

Require a careful environmental review

regarding ripios disposal and emergency

pond storage capacity

Design inputs from test work

Particle size

Agglomeration process

Uranium and gangue extraction extent

Reagent consumption rates

Leach cycle time

Irrigation rate, heap height and ore (fresh and spent) permeability

Heap Leach


Leach Test Work

Mainly used in acid leach; some

application on alkaline leach

Applied in safe locations

Applied to shallow sandstones with

acceptable permeability

Employs a perched selected

aquifer

Test bore is required to assist with predicting

Uranium recoveries and reagent utilisation

Gangue element extraction

Cycle time

In-situ Leach


Leach Test Work

Acid or alkaline

High temperature (70 – 95°C) or low

temperature (20 – 40°C)

Gas exhaust system needed to remove

radon for high grade ores

Feed to leaching may require thickening

to achieve a high pulp density


Temperature

Uranium and gangue element deportment

Reagent consumption

Residence time

Slurry density (35 – 70%)

Agitated Tank Leach


Leach Test Work

Acid (190 – 210°C)

Alkaline (110 – 120°C)

Low impurity levels in leach product

Oxidation via oxygen or air

Faster leaching kinetics and higher

extractions than atmospheric leach

Pressure Leach


Temperature

Oxygen partial pressure

Uranium and gangue element deportment

Reagent consumption

Residence time

Slurry density (35 – 70%)


Overview



Leach Test Work

Case Study




Case Study

Case Study:

Batch and Pilot Leach Tests

Agitation

Solid-Liquid Separation

Thickener

Filtration

Uranium Recovery

Ion Exchange

Solvent Extraction

Product Precipitation


Case Study

Case Study:


Agitation


Thickener

Filtration

Uranium recovery

Ion Exchange

Solvent Extraction



Case Study Leach Test Work

Batch test work Grind size

Temperature

Slurry SG

Pilot plant Leach efficiency

Reagent consumption rates

Materials of construction

Particle suspension (Agitation test)

Pilot plant set-up

Coupon test


Case Study Leach Test Work

Parameter Unit Value

Apparent viscosity mPa.s 300 – 2000

Slurry density %w/w 65 – 70

Specific torque Nm/m3 37 – 58

Power/unit value kW/m3 0.6 – 3.7

Baffle – aspect ratio 0.10 – 0.12

Impeller type Pitch blade

turbine

Surface response at 75%

solids

Surface response at

70% solids

Surface response at

65% solids

Agitation Tests


Case Study

Case Study:


Agitation


Thickener

Filtration

Uranium Recovery

Ion Exchange

Solvent Extraction




Thickeners

Prior to filtration

In lieu of filtration (CCD

arrangement)

Filtration

Vacuum belt filter

Pressure filtration

Non-Newtonian slurries resin in pulp has been used

Absorption

Elution

Barren slurry to tailings facility

Equipment


Case Study Solid-Liquid Separation

Settling flux vs. flocculant dose

Optimum settling performance at

feedwell solids concentration of

7.5% w/w

Underflow solids content vs.

Retention time

Thickener Test Work



Thickener Test Work

Underflow rheology

High rate thickener: 20 – 40 Pa

Deep cone thickener: 150 – 250 Pa

Other Data

Suspended solids: ~150 mg/L

Rise rate: ~8 m/h

Bed solids: 68 – 71 % w/w

Flux: 0.98 t/m2/h



Test work results:

Optimum flocculant dose: 75 – 140 g/t

Cake moisture: 15 – 20%

Optimum cake thickness: 19 – 24 mm

Drying time: 20 seconds

Flux: 1500 – 1600 kg/m2/h

Wash ratio: 0.8/tonne

Expected wash recovery: >98%

Filter Test Work

Vendor test work equipment

a) Vacuum belt filter

b) Pressure filter

a

b


Case Study

Case Study:


Agitation


Thickener

Filtration

Uranium Recovery

Ion Exchange

Solvent Extraction



Uranium Recovery Ion Exchange

Ion exchange

Fix bed

Carousel

Fluid bed


Case Study Ion Exchange

Continuous Ion Exchange Pilot Plant

Resin moves counter-current to

aqueous stream

Resin loading simulates tray loading

Suspended solids: 1000 – 3000 mg/L

Pilot plant confirmed:

Resin loading

Impurity element transfer

(NO3,F,Cl,etc)

Silica fouling and subsequent

regeneration


Uranium Recovery Solvent Extraction

Solvent extraction

Mixer settler Pulse columns


Case Study

Case Study:


Agitation


Thickener

Filtration

Uranium Recovery

Ion Exchange

Solvent Extraction



Case Study Product Precipitation

Sodium route to precipitate sodium diuranate (SDU)

Intermediate Product - Diuranate


Case Study Product Precipitation

Dissolution in sulfuric acid

Conversion to uranium tetraoxide

Final Product - Oxide

Element Assay

U 67.0%

K 0.02%

Mn 0.01%

V 0.09%

C <0.01%

Zr 0.02%

Th < 0.001%

Fe < 0.01%

Mo < 0.0001%

P < 0.001%


Overview



Leach Test Work

Case Study




Tailings - Geochemistry

Composition

Acid potential (AP)

Neutralisation potential (NP)

Net acid generation capacity (NAG)

Toxicity characteristic leach procedure (TCLP)

Kinetic test (ASTM D5744-96)

Radionuclides

Liner systems


Overview



Leach Test Work

Case Study





Radon-222 gas

Sealing and extraction ventilation of:

mills

leach tanks

Radium-226, Bismuth-214 and Lead-

214 can precipitate in sludges in the

solid-liquid separation equipment

Bismuth-214 accumulates in SX

circuits and cruds

Radium-226 present in aqueous

effluents


Thank You

role of test work in process engineering2013)_testwork_in_process_engine… · case study tailings...

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