An overview of fibre crop cultivation and multi-product value chains for post-mining

industrial development

CENTRE FOR BIOPROCESS ENGINEERING RESEARCH

STL Harrison, S Rumjeet, X Mabasa, M Solomon, B Verster

MINERALS TO METALS INITIATIVE

JL Broadhurst, T Chimbganda, G Hangone

Over 5900 abandoned mines in SA

Over 300, 000 job

losses since 1987

Significant loss of

biodiversityProblem

statement

Fibre crop potential

Exploring the potential of fibrous plants

Land remediation

potential

Metal recovery potential

Fibre-derived

products

fibre-rich plant

??

What are the downstream processing options for the recovery ofvalue from fibre plants?

Can fibre-rich plants serve the joint role of remediation of degraded mine land and fuelling of a multi-product value chain?

Key questions?

?

Proposed solution

Exploring the

potential of fibrous plants

Land remediation and metal recovery

Phytoremediation & Phyto-mining

Metal ions

Proposed solution

Exploring the

potential of fibrous plants

Fibre-derived products

Fibre

Additional products

Fibre

Woody tissue

Chemicals

Energy

fabric

cordage

piping

oils

bio-char

thermoplastics

bio-composites

pharmaceuticals

shives

Conversion

Lead products

Cultivation HarvestPre-

treatmentProductrecovery

Conversion

Plant

biomass

Fibrous-Part

By-products

SeedWater

Non-Fibrous-part

Fibrous-Part

Additional products

Conversion

Processing Manufacturing

Manufacturing

Biorefinery

Biorefinery

High-end

by-products

Potential System

Flowsheet

Scoping study and

investigation in

Carletonville, Rustenburg &

Witbank mining areas

Example site selection

Soil pH: 5.5 - 7

Average rainfall: 100 – 200 mm per

annum

Average temperature: 7 – 32 ℃

Gold

Coal

Platinum

Topsoil texture: Clay-sandy-loamy

Scoping study and

investigation in South African

mining areas

Overview and selection of fibrous plants in South AfricaFibre plants

Bast• Flax• Hemp• Jute• Kenaf

Leaf• Sisal• Palm

Seed• Cotton• Kapok

Fruit• Coconut

Wood• Pinewood• Baobab

Grass• Bamboo

• Non-invasive and/or indigenous

• Preferred soil type

• Temperature tolerance

• pH tolerance

• Multi-product possibility

Criteria for plant selection for example sites

Fibrous plants selectionBamboo balcooa, flax, hemp, kenaf and sisal• Higher metal concentration ability

• Metal selectivity

• More specific metal bioconcentration sites

• Wider range of fibre and seed based products

• Grow in warmer temperatures

• Relatively easier to cultivate

Plant selection criteria

Bambusa balcooa

400 – 5400 mm

9 – 35 ° C

12 – 18 tons/ha

M Pb, Zn, Cr, Fe

5 – 6 years

Flax

Pb, Zn, Cd

450 – 750 mm

10 – 27 ° C

~ 2 tons/ha

100 days

Hemp

Ni, Pb, Cd, Zn, Cu

500 – 700 mm

19 – 23 ° C

2.2 – 8 tons/ha

120 days

Kenaf

240 – 490 mm

15 – 27 ° C

5 – 7 tons/ha

Pb, Zn, Cd

90 – 125 days

Sisal

500 – 1500 mm

10 – 32 ° C

1 – 4 tons/ha

Zn, Cd, Cu

2 – 4 years

Selected fibrous plants for detailed study

• A wider range of products

• Stronger fibre (tensile strength)

• Fibre type :

Bamboo Hemp Kenaf

Hemp & Kenaf – Bast fibres

Bamboo – Woody grass

Scoping study and

investigation in South African

mining areas

Limitations and challenges

• Metal accumulation in fibrous plants tend tobe low

• Lack of top soil, organic matter and goodmicrobial dynamics on degraded land

• Metals can accumulate in harvestable parts of plants

• Product quality & safety would be an issue

• Return on investment may take long for someof the crops

Conversion

Lead products

Cultivation HarvestPre-

treatmentProductrecovery

Conversion

Plant

biomass

Fibrous-Part

By-products

SeedWater

Non-Fibrous-part(twigs, leaves, seeds etc)

Fibrous-Part

Additional products

Conversion

Processing Manufacturing

Manufacturing

Biorefinery

Biorefinery

High-end

by-products

Potential System

Flowsheet

STEM

ENTIRE PLANT SEEDS

LEAVES

Example: Hemp

Example - Bioethanol

Energy

Fibre + Woody tissue Leaves or Medicine

Bast fibre plant

processing

Bast fibre crop-to-product profile

Seeds Oilor

Woody tissue

Shives

Construction materials

Short Fibre

Cordage

Paper Pulp

Long Fibre

Bio-compositesBast Fibre

Hurd

&

&

Bast fibre stem cross-section

Conventional textilesIntermediates End-products

Plant

Textiles

Woody tissue

Stem FibreStemHarvest Pre-

treatmentProduct recovery

Spinning

Conversion

Long

ShortCarding

Pulping

Cordage

Composites

Paper

Sorting

Pulping Paper

Conversion

Shives

Seed oilCleaning

Compression

Construction materials

Leaves Cleaning

Conversion

Whole leaves

Seeds Whole seeds

Fibreproducts

Woodytissueproducts

By-products

By-products

Medicine

Bast fibre multi-product flowsheet options

Spinning

Conversion

Carding

Pulping

STEM/CULM

ENTIRE PLANT BRANCHES

Example - Biochar

SHOOTS

Energy

Wood or Fibre or Pulp

Household wood products

Vegetable

Bamboo plants and

processing

Bamboo crop-to-product profile

Fibre

Natural

Rayon

Pulp

Cardboard

Paper Pulp

Wood

OR

OR

Poles

Wood products

Bamboo culm/stem

Intermediates End-products

HarvestPlant

Plybamboo/

Burning

Pulping

Energy

Board making

Splitting

Option 1a

Low quality stems/wastes from options 1 and 2

Whole plant (100%)

Top of culm

Culm (80%) High-end

products

Strand woven boards

Bamboo mats

Particle board Low-End or bulk

products

Fibre recovery

Weaving

Board-making

High quality stems

Option 1b

Option 2a

Board making

Natural fibre

Option 2bMDF boards/Poles

Medium quality stemsPre-treatment

Bamboo mat boards

Paper pulp Option 3a

Option 3b

Option 3c

Medium-value

products

Bamboo multi-product processing scenarios

Leadproducts

Cultivation HarvestPre-

treatmentFibre-

recoveryPlant Fibrous-Part

SoilWater

FibreFibrous-Part

Additional products

Manufacturing

Non-fibrous parts

Potential integrated metal recovery process

Leachate (metals)

(metals)

AshingBio-ore

Hydrometallurgical/pyrometallurgical

extraction Metals

Plant-synthesised nano-catalysts

Manufacturing

Summary of fibre

processing and product

selection

• Selection of product recovery and treatment processes is highly dependent on desiredlead and additional product types.

• All the fibre-producing plants can generate multiple products however, the range ofproducts differ for the different plant types.

• Exploitation of fibre-based plants and industry development will also depend on thesocio-economic and environmental drivers.

• Integrating metal recovery may limit product quality and the capability of the fibreproducts.

Summary

Acknowledgements