Basdew Rooplal

Pre- feasibility study of a low grade / sub economic Iron ore

deposit

Contents

1. Introducion

2. Analysis of Given Information

3. Preliminary flowsheet options

4. Testwork Program

5. Other factors for consideration

6. Examples of detailed flowsheets

7. Conclusions

8. Recommendations

Introduction

• This is a Greenfield project in the Northern Cape, with an exploration licence.

• Available information after a year of exploration drilling and conceptual phase results:

• Discovered resource size enough for 25 years at a planned product rate of

• 30 000 000 tons product per annum.

•

• Low grade ore with a % Fe in resource varying between 40% and 50%.

• Conceptual phase results indicated a possible top size of 6.3mm.

Aims and Objectives

• To Outline a program that will take the project from a conceptual stage to the feasibility stage.

Given info – Production / Grade

• Production– 30 million tons per

annum– 2.5 million tons per

month– 100 000 tons per day– 4000 tons per hour

• Grade • 40 – 50 % Fe• On grade• > 65 % Fe• Off Grade• > 60 < 65 High• > 39 < 60 Low• Waste• < 39 % Fe

Size Distribution

• Given < 6.3 mm• > 10 mm subjected to

direct smelting

• Possible upgrade methods available < 10 mm

• Gravity Separation• Magnetic Separation• Flotation• Online elemental

analysis / Scanning

Gravity Separation

• Mineral Densities• Hematite 5.1• Magnatite 5.2• Goetite 4.2• Siderite 3.8

• Gangue 2.65• Cut Point 2.9 – 3.2

• Equipment Available• DMS Cyclones - 120 tph• - 6 + 0.2 mm• Batac Jigs 500 tph• - 30 + 0.5 mm• Spirals 3 tph• -1 + 0.03 mm• Tables 2 tph• - 1 + 0.03 mm

Magnetic Separation / Flotation

• Wet / Dry Magnetic Separators

• High Intensity • 7 000 – 20 000 Gauss• Medium Intensity• 2000 – 7000 Gauss• Low Intensity• 1000 – 2000 Gausss

• Flotation• - 65 micron Fraction• Fatty Acids• Petroleum sulfonate

collectors

Online Elemental Analysis / Scanning

• Khumani Iron ore• Elemental Analysis• Fe

• Al2O3

• K2O + Na2O

• SiO2

• Estimated Yields• Ongrade > 80 %• Off Grade High• >65 < 80 %• Off Grade low• > 45 < 60 %

Flowsheet Options – Elemental Scanning

ROM Elemental Analyser

On Grade > 65% Fe

Waste < 39% Fe

Off Grade >39 < 65 % Fe

Crushing / ScreeningCrushing / Screening

Further Beneficiation

Pelletiing Smelting

Off Grade Beneficiation Option

Crushing / Screening

Jigs / DMS Spiral / Tables

WLIMS / WHIMS

+1 mm - 1 mm

CoarseConcentrate

Regrind / Ball Mill

WLIMS / WHIMS

TailsTails

Tails

Fine Concentrate

Tailings to Waste

Waste < 39 % Fe Option

Tailings from Elemental Scan

Tailings from WHIMS

Tailings from Spirals

Semi Autogeneous Milling

Flotation

Filteration / Pelletising Thickeners / Slimes Dam

TailsFloat Conc

Testwork Program

• Elemental Analysis• XRF X-Ray florence

spectroscopy• Necessary to determine

the components of the mineral and its behaviour during processing

• Mineralogy• QEMSCAN, MLA, X-ray

diffraction (XRD), HyLogging and optical microscopy

• Important in choosing the method of upgrading via comminution, gravity, flotation and/or other beneficiation processes

Testwork Program

• HyLogging • spectral analysis

technology for rapid, automated scanning of iron ore drill core, chips and powder.

• This technology is used for a range of applications from logging and archiving core, mineral exploration, and mine planning, to geometallurgy and mineral processing

• The instrument generates digital images and surface spectra which is interpreted by software to produce mineralogical information.

Metallurgical Testwork

• 15 metre drop test to estimate lump/fines ratios and the particle size distribution expected from blasting and processing

• Lump and fines products - beneficiation testwork or characterisation

• iron ore physical testing- Tumble Strength Testingo iron ore thermal testing- Reduction Disintegration Index - Reducibility - Decrepitation Index

Metallurgical Testwork

• Magnetite testing, including wet and dry magnetic separation (LIMS)

• Beneficiation testing - spirals, up-current classifiers, jigging, WHIMS

• Flotation testing - direct and reverse for silica removal

• stage pulverized and optimisation tests versus grind size

• Magnetic susceptibility

• Densimetric testing• Granulometric• Online measurement

& Ore sorting technologies

Metallurgical Testwork

• Agglomeration including pellet and sinter testing

• Wet and dry rare earth drum capacity

• Advanced screen

• Comminution– Autogenous media

competency– Bond abrasion index– Bond ball mill work index– Bond impact crushing work

index– Bond rod mill work index– Comparative work index– High pressure grinding rolls

(HPGR

Metallurgical Testwork• JK drop-weight test and SAG

mill comminution (SMC) test• Levin open circuit grindability• Point load test• SAGDesign (Starkey)• Ultra fine grinding• Unconfined compressive

strength

• Pilot testing• Bulk crushing and screening• AG/SAG milling• Ball milling• HPGR• Hydrocyclones• Spiral Pilot Rig • Magnetic separation• Dense medium cyclone plant• Gravity separation• Flotation• Scrubbing• Dewatering and tailings

management

Other Investigations

• Logistics of transporting of finished products

• Water management requirements

• Power and raw material requirements

• Skilled labour manning and training

• Waste material storage capacity and management

• Opportunity for other value add benefits at the source

Detailed Flowsheet

360 – 800 tph WHIMS

Comparison of Underbed / Side air pulsed Jigs

Conclusions

• Careful consideration should be given to the Elemental and mineralogical Analysis as this can yield valuable design information

• Well chosen combinations of gravity and magnetic separation units can provide for successful upgrade methods for a low grade deposit.

• Conceptual phase of logistics of ore / product transportation and movement needs to be completed as large volumes are under consideration.

• Conceptual requirements for process water to support a Wet processing plant needs to be evaluated.

Conclusions

• Lab scale testing will provide sufficient results for a pre-feasibility stage

• Process simulation and pilot tests should be carried out during the feasibility stage for more accurate results.

• Sufficient Consideration should be given to Elemental scanning techniques at source or at an early stage of the flowsheet as this can reduce the volume to be processed and capital cost.

Recommendations

• Sufficient work should be put into the logistics of the project.

• Laboratory scale test work should be carried out on process beneficiation techniques using elemental scanning / gravity separation and wet magnetic separation techniques on available material.

• More emphasis should be placed on elemental and mineralogical Analysis at this stage of the project.