denim return project an investigation of the recycling and

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Denim Return Project Final Report

Bradmill Undare Group 1 11/1/1999

Denim Return Project: AnInvestigation of the Recycling and

Reuse of Denim Waste


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Author

Bradmill Undare Group

Denim Park

341 Francis StreetYARRAVILLE VIC 3013

Tel: (03) 9274 6200; Fax: (03) 9274 6201

Acknowledgements

Thank you to the following companies/organisations who provided support, expertise and

resources, which enabled this project to be completed.

Texskill Smith Family Industries EcoRecycle Victoria Bradmill Undare Group

Disclaimer

This report has been prepared for EcoRecycle Victoria by the Bradmill Undare Group. The viewsexpressed in this report are not necessarily those of EcoRecycle Victoria.

The contents of the report are provided for information purposes. EcoRecycle make no claim as to the

accuracy or authenticity of the content of this publication and does not accept liability to any person for

the information or advice provided in this document or incorporated into it by reference. EcoRecycle

does not accept liability for loss or damages incurred as a result of reliance placed upon the content of

this document. The document is provided on the basis that all persons accessing it undertake

responsibility for assessing the relevance and accuracy of its content.

Date

January 1999

Publishers

EcoRecycle Victoria

Level 4, 478 Albert Street

EAST MELBOURNE VIC 3002

Tel: (03) 9639 3322; Fax: (03) 9639 3077

Email: [email protected]

Web site: www.ecorecycle.vic.gov.au


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Project Title: The Denim Return Project

TABLE OF CONTENTS

TABLE OF CONTENTS 3

Background: 4

The Project Objectives: 5

PROJECT RESULTS: 6

1. The form of denim (and other cotton) wastes 6

2. Examination of reuse and recycling options for denim 8

2a). Recycling denim wastes into recycled denim 8

2b) Paper manufacture 9

2c) Paper Board manufacture 10

2d) Shredding for fill 10

2e) Shredding for adsorbent applications 10

2f) Combustion of wastes 10

3. Establishment of a return service for scrap denim to Bradmill Undare customers 11

3a) Survey of Victorian customers 12

3b) Estimated quantities of denim wastes recoverable 12

4. Analysis of denim waste reuse options 13

4a) Paper and board making 13

4b) Merchant applications 13

4c) Combustion 13

4d) Recycled yarn manufacture 13

5. Recycled yarn production 14

CONCLUSION 15


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Project Title: THEDENIM RETURN PROJECTAn Investigation of the Recycling / Reuse of Denim Wastes

Background:

Bradmill Undare manufactures a range of denim fabrics that are sold locally and exported.

Denim wastes are generated such as warp tailings, denim selvedge, fabric scraps and other

smaller wastes. Denim wastes are also produced by Bradmill Undare customers in their

garment manufacturing operations.

This project has investigated opportunities for the recycling and reuse for denim wastes and

to provide this as a total recycling / recovery service to Bradmill Undares customers as well

as fulfilling a need for waste reduction at the Denim Park facility. Recycling and reuse

options set up at Bradmill Undare may provide better and more economic methods of waste

denim usage for Bradmill Undare and its customers.

In the past Bradmill has been involved in yarns spun from cotton wastes. It had a

dedicated waste spinning line that produced a range of yarns up to 300 Tex (for mop yarn).

This line was fed by motes and other cheap cotton fibre. This plant also produced open

ended (OE) yarns for weft in a low end denim product. This line was sold off when

management decided to concentrate on the high quality end of the denim market. These

operations did not include fibre reclamation from hardwaste1.

With the development of a greater industrial environmental awareness, this situation may

need to be reversed and Bradmill has decided to look at the waste issue includingopportunities for reuse of denim wastes.

The opportunities for denim reuse that this project has investigated are:

1. Shredding and recycling into a new spinning operation2. Shredding and reuse as a fibre base for paper and cardboard3. Sorting and packaging for sale locally and overseas4. Briquetting for combustion in Bradmill Undare boilers5. Shredding and use as filling material for a range of non-woven applications including

wadding for furniture, cushions and pillows, car wadding6. Shredding and use in mushroom production7. Shredding for use as an absorbent material (mainly for oil spills)8. Use of larger scraps as polishing rags

1Twisted fibres e.g. yarn or fabric. Opposite to softwaste which is loose fibre.


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The Project Objectives:

The objectives are to study options for the recovery and recycling of denim wastes and to

maximise the economies and opportunities by applying this to the supply chain from denim

manufacture through to the finished garment.

In this the following objectives may be stated:

1. To maximise the opportunities for denim waste recycling and

hence to reduce landfill wastes

2. To provide the best options for denim waste reuse to large

and small denim users

3. To reduce wastes and maximise product recycling, fibre and colour

recovery


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Project results:

1. The form of denim (and other cotton) wastes

Bradmill produces fibre wastes in various forms from its cotton and Tencel processing

operations. Bradmill Undares clients produce cutting wastes from garment cutting and

make-up operations. The nature of the wastes is important in the form of the final use that

they can be put to.

The basic split in fibre wastes is between hard wastes in which the fibre has been spun

and soft wastes in which the fibre has not been spun. Bradmill client wastes are all hard

wastes, which need to be pretreated before they can be respun.

Fibre length is critical to the end application: short fibre lengths less than 3-4 mm cannot berespun, but may be used for a range of other applications including non-wovens and paper

manufacture where short fibre length is a requirement. Longer fibres may be suitable for

respinning, although the condition of the fibre is again important: stressed fibre will break

easily and cause further wastage.

Impurities are also an important aspect of fibre reuse. Mixed fibre types reduce reuse

options, dirt and vegetable matter have to be removed and metal contamination can cause

serious hazards in reprocessing.

In weaving operations yarn is sized with a starchy material. Sizing has to be removedbefore respinning, which adds considerable cost to reprocessing operations. This may also

affect the recyclability of waste yarns. Sizing will affect fibre absorbency , which will reduce

its effectiveness in oil spill collection, paper production and may reduce its usability in other

non-woven applications.

Colour in fibre can have a positive, or a negative effect on its recyclability. Coloured fibre

has to be bleached before it can be used to manufacture high quality white paper. Indigo

used in blue denim is difficult to apply to the fibre and difficult to remove through

bleaching. However, the residual colours in denim fibre may enhance the final product if it

has a particular application. Recycled denim has been used to manufacture denimcoloured paper, denim pencils and other stationery items.

Recycling operations in Europe use coloured fibre sorted into colours for respinning. Careful

colour mixing of fibre flocks can achieve specified colours in final spun yarns without

requiring dyeing. This type of operation has a minimum economic input of approximately

250 tonnes of cotton wastes per month. (Bradmill produces approximately 20 tonnes per

month.).


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A basic breakdown of reuse fibre requirements is given below:

APPLICATION FIBRE CHARACTER

SHORT LONG COLOURED SIZED METAL

CONTAM.

Respinning for

coloured yarn ra a

Desizing

may be

required

r

Respinning for denim

ra

Blue is okay

(maybe black)

Desizing

required r

Paper productiona

r

May require

bleaching a rPaper board

production

a a a a

r

Shredding for fill

a a a? r

Shredding for

absorbenta a a

r r

Combustion

a a a a aNon-woven

a a

May require

bleaching

May

require

desizing

r

Rags scraps

8 cm sq.

(min) a aN/A

Mushroom production

a a a ar

Note: Note that there are various types of denim wastes, some are coloured, others have

size on them, some are spun and others are soft wastes. Denim fabric and selvedge mayhave some contamination with synthetic and other non-cotton fibre.

It is not surprising that the respinning represents the highest level of value adding to the

recycled fibre and combustion the lowest.


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2. Examination of reuse and recycling options for denim

This part of the project has been undertaken over a number of years already as both

Bradmill Undare and its customers have looked for alternative measures to tipping denim

wastes.

The base option against which all other reuse options will be measured is the resale of denim

wastes on the open international market. Bradmill Undare has been approached by

merchants who wish to purchase these wastes and Bradmill Undare may act as a central

collection and distribution point.

Rags sell on the international market for varying prices, depending on whether they are

colour sorted, clean and the fibre composition. Cotton rags, colour sorted from middle

Europe could be obtained free on board (FOB) for about US$0.50 / kg at the time of

writing.

Approximate pricing for recyclable fibre in various forms is given below:

TYPE AUSTRALIAN

OF WASTE DOLLAR VALUE

Pure cotton (from Ginners) $2.40 /kg

Cotton Rags (Australia) $0.42 / kg

Raw floc


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Textilindustrie Vol. 40 / 92, Sep. 1990. Bradmill has examined some of these technologies

and is continuing to develop its own reclamation and respinning systems.

Anecdotal reports suggest that the Italian textile industry has a thriving recycling component.

An international textile trading company representative said that the throughput for a viable

fibre reprocessing industry was approximately 250 tonnes of fibre / month.

Some levels of contamination with synthetic fibre can be tolerated in recycling as long as the

yarns do not have to be dyed.

2b) Paper manufacture

We approached the two large paper manufacturers:

- Visy

- Amcor

We also held meetings with the CSIRO scientists on opportunities for waste fibre

reprocessing. The general conclusions reached were:

1. A minimum batch size of 200 tonne was required for paper manufacture

(Visy estimate).

2. Coloured waste fibre would have to be bleached for high quality paper

(Denim uses Indigo colouring, which can only be bleached using chlorine).

3. Fibre lengths have to be kept short and pre-pulp shredding would be

needed.

4. Synthetic fibre contamination would not be tolerated in significant amounts.

5. Cotton wastes would have to be chemically treated in order to pulp properly

6. Recycled paper prices were low because supply exceeded demand so there

was little incentive for the paper companies to look at this waste material.

Even though cotton fibre can produce superior paper qualities.

Bradmill approached the Shire of Benalla who are planning a pulp mill for paper production

from fast growing crops and may be able to use cotton wastes to top up crop yields. There

were a number of other crop wastes to paper projects identified, but it was unlikely that

these processes would pay for cotton wastes.

Another pulp mill is planned for Horsham. This is intending to use straw as the raw material

for paper pulp. Transport costs would prevent an economic transfer of cotton wastes into

this process.


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2c) Paper Board manufacture

The requirements for paper board manufacture are much less stringent as the paper board is

a lower grade of product with a lower value per kg. Van Leer Industries was approached

and did do some laboratory trials with mixed cotton wastes from Bradmill.

These were not successful and it was concluded that the cotton wastes would have to be

chemically treated in order to pulp properly. As Van Leer did no chemical pretreatment of

its recycled paper it was unable to accept these wastes.

2d) Shredding for fill

Bradmill has sent a good deal of its waste fibre to a scrap merchant for final use as a fill

material in mattresses, car headlining and other filling applications. The merchant cut the

wastes, they were then shredded and blended.

The merchant has indicated that sized fibre is no longer suitable, selvedge demand has

dropped and hessian bags previously recycled were also not suitable for reuse due to metal

contamination with wire used to attach tags. This may have also been the result of low

demand for these wastes.

It is understood that the companies using this fill import rags and fibre as well as purchasing

locally, but the application is limited and demand is reliant on the end applications continuing.

2e) Shredding for adsorbent applications

Shredded cotton is a good absorbent and a company in Sydney is purchasing cotton wastes

and shredding them for this application. Again the market is considered to be very limited

and of low value.

2f) Combustion of wastes

Bradmill has purchased a briquetting machine to compact unreprocessable cotton wastes

into small briquettes for combustion. This application has an even lower value atapproximately 4c/kg, which is still preferable to landfill at a cost of about 9c. per kg.

Combustion problems were experienced in trials:

- the cotton briquettes broke up in coal bunkers and fouled the hoppers

- water used to quench the coal dust caused the briquettes to swell

- feed hoppers were choked with cotton

- there was a fear that the cotton dusts would coat tubes and reduce heat transfer

- boiler operators suggested that the cotton trash generated smoke in stack emissions


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Cotton briquette combustion characteristics were examined by RMIT laboratories using

thermal gravimetric analysis (by Dr. Shanks, School of Applied Science) and the results are

summarised below in comparison with published figures for coal (energy brix) :

Property Coal (energy brix) Cotton briquettes

(3 samples analysed)

Moisture content 10-14 % 7-10 %

Ash 1-2 % 5.9-8.5 %

Heat value 22,500 kJ/kg 11,000-14,000 kJ/kg

Combustion range 900-1100 C 350- 600 C

Compressive strength 180 kg/cm2 not tested

The cotton briquettes appeared to combust satisfactorily in comparison with the coal

briquettes (energy brix) currently used in the Bradmill boilers. Moisture content of the cottonbriquettes was below that expected for the coal, while ash residues was 4 times higher than

that of coal. Heat value of the cotton briquettes was just over half that of coal and full

combustion would be expected in boiler temperatures exceeding 600 C.

Ash content may be a concern as this may have an effect as a deposit on tubing, but the mix

of coal briquettes to cotton would be at a very high ratio. (3 tonnes of cotton briquettes per

week compared to 440 tonnes of coal briquettes per week.)

Trials have been recommenced to see if deleterious effects are evident with prolonged

cotton briquette usage. Due to hopper problems the cotton briquettes are being shoveledmanually into the furnaces and a dedicated feed system will be required if this operation

proves successful. Bradmill Undare is also looking at using briquettes made from wood

dusts.

3. Establishment of a return service for scrap denim to Bradmill Undarecustomers

While Bradmill Undares waste volumes for denim may total 5,000 kg per week, its

customers also produce denim waste. If this is consolidated at one point through a returnsystem the reuse options will have a higher volume and better economics.

This also provides a way for smaller companies using denim to become involved in waste

reduction through recycling without the need of setting up their own programs. Bradmill

Undare will be providing further value to its products by taking away wastes.

Return systems for denim wastes will have to be organised and communications of options

for customers provided in an information kit on denim return. It appears that the project will

best be piloted on local customers who are serviced by Bradmill Undares own delivery

trucks. If this proves viable it can be extended to interstate customers.


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3a) Survey of Victorian customers

We undertook a survey of Bradmill Undare customers in Victoria to see if they could hold

cotton/denim wastes for collection and recycling. We surveyed 82 Bradmill Undare

customers, most of whom are small garment manufacturers. A response was obtained from

29, or 36% and a significant percentage of the remainder were managing agents and notmanufacturers themselves, they subcontracted out the manufacturing of garments.

Of those who responded the overwhelming majority were either interested in this recycling

program, or were already involved in another recycling program. The larger customers

reused scraps internally, or had an arrangement with a recycler to take away the scraps

without charge, or payment.

Other recycling systems mentioned were:

- recycling as insulation- rags used for cleaning

- used as stuffing in toys.

Contamination of the denim wastes was an issue for some of the garment manufacturers who

used other materials such as polyester. Others reported contamination with marking paper.

60% of these responding said that they could easily segregate the cotton wastes for

collection.

There was also an option established to take other cotton wastes from these garment

manufacturers. Some of whom purchased other denim fabrics and others who produced nondenim garments.

3b) Estimated quantities of denim wastes recoverable

The quantity of denim wastes from Bradmill customers has been estimated as follows:

Surveyed customers Sales/ week 4,790 metres Wastes 253 kg /week

Total Australian sales 50,000 m. 2,600

The weight of 1.2 metres of denim is approximately 1.0 kg, therefore the wastage factor for the

garment manufacturers is 253 kg for 4000 kg of material processed, or 6.3%.

In 1996 Bradmill processed 10,000 tonne of cotton. It produced 6 million metres of denim weighing

5,000 tonne. Bradmill generated 250 tonne of cotton wastes while its Australian customers produced

an estimated 130 tonne of waste denim.

The total potentially recoverable denim / cotton waste is then 380 tonne / year.


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4. Analysis of denim waste reuse options

4a) Paper and board makingThe potential recovery of 380 tonnes of denim wastes in a year precludes major efforts in

terms of paper manufacturing at first pass unless the denim is added to another substrate for

the production of a diluted paper, or cardboard.

The economics of paper manufacture in large commercial quantities would require storage

and accumulation of these wastes for the better part of a whole year.

Small paper and board manufacturers do not use chemical pretreatments before pulping if

they are using recycled paper. These operations cannot therefore handle cotton wastes.

4b) Merchant applications

These applications include rags, filler applications and use as absorbents. They suffer from

variation in demand and do not command premium prices for the waste cotton, $0.10 to

$0.50 per kg.

The off-cuts from cutting table wastes generated by Bradmill Undare clients are generally

small, less than 8 cm. sq. which reduces their value to the low end of the range above. If an

average value of $0.15 per kg is realised this would have to cover the costs of segregation,

retrieval and storage before an economic service could be developed.

4c) Combustion

This is only an option for internal Bradmill Undare cotton wastes for spinning operations.

With a net value added of $0.13 per kg, over disposal to tip, this reuse of cotton trash is

economic if technical problems can be overcome.

For this reason extended trials are in progress.

4d) Recycled yarn manufacture

The production of recycled denim yarn is the best option for denim scrap reuse as it

provides the highest value adding potential.

Respinning for denim yarn manufacture may make economic sense, but it appears that there

is not sufficient waste denim to support an independent fibre recycling facility. There may be

sufficient to run a small recycling unit within a larger spinning operation, such as at Bradmill

Undares Denim Park facility.

The marketability of a recycled denim yarn, or a recycled denim fabric is critical to the

success of such a project.


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A superficial market survey was conducted within Bradmill Undare with the following

outcomes:

There was general interest in the concept Technical problems may need to be overcome:

usable yarn finess excessive fabric pilling adequate yarn strength poor processing efficiency excessive shrinkage depth and consistency of colour

There may be an opportunity in a course knitting yarn which does not suffer fromas many technical restrictions

Recycled yarns may only find niche markets and in fact care must be taken withAustralians as the term recycled may turn them away (verses Europeans which

react more favourably). This implies that market positioning should be based on

price, performance and uniqueness.

Selling price for a recycled yarn may be between $4 and $9 per kg Vertical integration by manufacturing a recycled denim was suggested

The case of Burlington Mills who recycled used denim into yarns was quoted as being of

only marginal value to the firm.

5. Recycled yarn production

In first round trials Texskill has produced a sliver from a recycled denim scrap floc. Some

technical difficulties had to be overcome, but the results were promising. The sliver was

tested at the Bradmill lab and showed good eveness and fibre length.

The waste used in this first trial was not prepared in a scientific manner, so a second round

of trials was prepared with fresh samples of denim wastes.

Six bales (1200 kg) of waste were garnetted/flocked by the Smith Family Industries and

made ready for spinning trials. These are:

Sample Description

Mix A - Indigo Designed to maximise the depth of indigo

colour.

No black.

100% cotton

Mix B - Natural No colour

100% cotton

Mix C - Full Representative of all types of denim wastes

Includes some synthetics

No woolNo black


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Mix D Blend of Mix A (90%) to 10% virgin cotton.

Bradmill Undare undertook a series of detailed trials and development work in conjunction

with Texskill facilities.

The trials were successful in that a range of open end (OE) yarns were produced in several

sizes (42 to 98 Tex) and from Mix A, B and D. The yarns were of acceptable quality and

colour, although some issues of plant efficiency and process yield need to be addressed.

Further yarn conversion is planned for January 98 and fabric/garment sampling in February

98. These samples will enable further technical, market and business evaluation. Note that

capital expenditure in specialist plant would be needed to produced these yarns on

commercial basis.

CONCLUSION

This project has demonstrated an interest in return of wastes from Bradmill Undare

customers, who are keen to participate in waste reduction and recycling programs.

Reuse of denim wastes has taken a traditional path of least resistance where uses involving

minimal reprocessing have been adopted. This has lead to low value end uses and low

prices for denim wastes.

Transformation of denim wastes into new and novel products appears to be too costly,while the production of paper, although not difficult technically, is not practical due to the

duopoly structure of the Australian paper industry.

The key to economic waste reuse is in adding value by respinning denim wastes into yarns

that are either developed into a recycled denim, or as knitted fabrics that go with traditional

denim garments.

A range of reclaimed denim yarns has been successfully produced by Bradmill via this

project, however, further development and trial work is required to overcome a number of

management, technical and market hurdles before it can be developed commercially.

Production efficiency Production yield Garment performance assessment Market assessment and scoping Yarn specification Economic analysis (capital investment will be required).

When these activities have been completed Bradmill Undare management will determine the

future direction of this initiative.

denim return project an investigation of the recycling and

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