Glass Recycling

7/21/2019 Glass Recycling

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TECHNICAL NOTE NoRECYCLING OF GLASS

14

Technical Note 2

Technical Note 6

Treatment of finalwaste

Technical Note 11 Technical Note 12

Recycling ofplastics

Technical Note 13

Technical Note 8

Principles for SSWM

Evaluation of theneeds for SSWM

Technical Note 1

Technical Note 3

Selection of technicalcomponents for the

establishment of a stra-tegy for SSWM

Technical Note 4

Organisation andoptimisation ofwaste collection

Technical Note 5

Technical Note 9

Micro-composting andseparate collection ofbiodegradable waste

Recycling as a wasteteatment option

Management ofhazardous waste

Technical Note 7

Composting stations

Technical Note 14

Technical Note 10

Anaerobic treatmentof organic waste

Recycling of glassRecycling of paper andcardboard

Recycling of non-ferrous metal



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RECYCLING OF GLASS

TABLE OF

CONTENTS

Technical Note 14

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TABLE OF CONTENTS............................................................. 1

LIST OF FIGURES.................................................................... 1

LIST OF TABLES....................................................................... 2

LIST OF ACRONYMS............................................................... 3

TECHNICAL NOTE NO 14....................................................... 4

RECYCLING OF GLASS........................................................... 4

1. Glass under its various forms...........................................4

1.1. Production and composition........................................... 4

1.2. Types of products...........................................................6

2. Glass recycling channels................................................11

2.1. The manufacturing channels...........................................12

2.1.1. Optimization of the deposit-and-return (DaR) system..........13

2.1.2. Optimization of colorimetric sorting.................................15

2.1.3. Optimization of the collection of clear glass and flat glass... 18

2.2. Alternative recycling options........................................... 21

2.2.1. A complementary strategy with a local dimension.............. 21

2.2.2. The integration in concrete and other construction material.22

LIST OF FIGURES

Fig 1: Representation of the colorimetry of glass according to

the addition of metallic oxides......................................... 5

Fig 2: Representation of different modes of production

of glass........................................................................ 7

Fig 3: Different types of flat glass...............................................8

Fig 4: Different types of container glass..................................... 9

Fig 5: Different types of fibre glass.............................................10

Fig 6: The three colorimetric groups..........................................16

Fig 7: Glass shredding............................................................16

Fig 8: Typology of clear glass................................................... 19

Fig 9: Selective sorting of clear glass......................................... 23



Fig10: Representation of the production cycle for cement with addition

of recycled glass............................................................ 24

LIST OF TABLES

Tabl 1: Chemical composition of different types of glass................ 6

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TABLE OF

CONTENTS

RECYCLING OF GLASSTechnical Note 14

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TABLE OF

ACRONYMS


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ABS Acrylonitril butadiene styrene

CFC Chlorofluorocarbons

DAR Deposit-and-Return

EC European Commission

ECS Eddy Current Separator

GDP Gross Domestic Product

GHG Green House Gases

ICZM Integrated Coastal Zone Management

IOC Indian Ocean Commission

LCD Liquid Crystal Display

MSW Municipal Solid Waste

NCV Net Calorific Value

NFM Non Ferrous Metals

NFP National Focal Point

NHIW Non Hasardous Industrial Waste

PCB Polychlorobiphenyl

PCM Project Cycle Management

PEhd Polyethylene high density

PEld Polyethylene low density

PET Polyethylene terephtalate

POP Persistent Organic Pollutant

PU Polyurethane

ReCoMaP Regional Programme for the Sustainable Managementof Coastal Zones of the Indian Ocean Countries

SME Small & Medium Enterprise

SWM Solid Waste Management

TN Technical Note

TOE Ton of Oil Equivalent

WEEE Waste Electrical and Electronic Equipment

PP Polypropylene

TOR Terms of Reference

PVC Polyvinyl chloride

HHW Household Waste

PS Polystyrene



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The glass is a discrete but omnipresent material. It is present in many

consumer goods and equipment, both as pure and impure material.

1 Glass under its various forms

Production and

composition

1.1

In fact, there are numerous types of glass which decline according to the

applications which are made, but the material itself present some1

inherent characteristics associated to the composition of the product :

At its origin, glass is composed of sands containing more than

99% of silica (SiO ) which plays the role of oxide forming the2

molecular structure to the networkSilica counts for about 72% in the composition of the average

glass material.

Purer sands containing low impurity level (< 0,2% of iron oxide)

are reserved for the elaboration of optical glass and crystal

manufacture.

The sodium carbonate brings the main oxide which modifies the

molecular structure of the network (Na O) and which plays the2

role of melting agent allowing the reduction of the melting point

of SiO .2

1 from J. Zarzycki « les verres et l'état vitreux, Masson 1982. »

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Under the form of bottles and other

containers it is a pure (or nearly pure)

material which constitute the totality ofthe product

In the hull of a fibreglass boat it

constitutes only a fraction, invisible and

not often disregarded.


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Figure 1: Representation of the colorimetry of glass according to the addition of metallic oxides.

Limestone and dolomite bring calcium carbonate (CaCO )3

which improves the chemical resistance of sodic glass by strongly

reducing their solubility

The borax (2B O + Na2O) brings the oxide of Boron (B O )2 3 2 3

which reduces the dilation coefficient of glass and improves its

resistance to thermal shocks.

Minium (Pb3O4) brings the lead oxide (PbO) which increases therefraction index. We can note that in the crystal glass, the PbO

content is higher then 24%. With a high content (48 to 80%), it is

used in optical glasses and those which protects against X-rays.

For more than 20 years, a large fraction of glass production has been

carried out from recovered and recycled glass, also called cullet. In

2005, in average 64% of glass produced in Europe was made of recycled

glass and this proportion is increasing. The furnaces for production of

hollow glass commonly use a mixture which contains more than 50%

cullet, the average for flat glass being 20% only. Some furnaces morecommonly used for green bottles can use up to 90% of cullet.

The color of a glass is given by the metallic oxides which are

incorporated:

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Iron and chrome oxides Nickel oxides Iron sulphite in reduction phase

Manganese oxide Cobalt oxide Copper oxide

Green Brown Ocre

Purple Blue Red and Blue-green



Chemical composition of the maion types of glasses

Types

flat glass

container glasse

"pyrex"

fiber glass

"Kristal"

glass for bulbs

SiO2 B O2 3 Al O2 3 Na O2 K O2 CaO MgO PbO

72.5 1.5 13 0.3 9.3 3

73 1 15 10

80.6 12.6 2.2 4.2 0.1 0.05

54.6 8.0 14.8 0.6 17.4 4.5

55.5 11 33

73 1 16 1 5 4

Table 1:Chemical composition of different types of glass

Beyond the variability in the chemical composition of glass, we must also

take into account the fact that this material covers a wide range ofindustrial applications which can be distributed in 3 main groups:

Flat glass

Container glass

Glass fibers

In each group much diversified products are found but they share the

same particular mode of production. We can also note that the three

groups use cullet in different proportions to optimize their production:

Types of products1.2

As for ferrous /non-ferrous metals, plastics and paper/cardboard,

glass recycling forms an integral part of the life cycle of a glass product

From a general point of view, we must underline that glass production

has a very high energy consumption due to the transformation of silica

(in majority) which requires temperatures around 1500 °C to reach its

melting point. We can note that the melting point of cullet is of

1000°C only which represents an economy evaluated at 1 TOE for

10 T of cullet

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Figure 3: Representation of different modes of production of glass

The following figure illustrates the different channels for glassproduction:

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The group of flat glass products counts 8 types of different glasses as

represented below:

Figure 3: Les différents types de verres plats

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Container glass products can be divided in three sub-groups:

Figure 5: Different types of container glass

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Figure 5: Different types of fibre glass

Fibres include two main types:

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Textile fibersTheir composition is very poor in alkaline oxide but encompasses high quantitiesof alumina, Anhydrate Bore and some mineral alkaline oxides

Builiding and composite sector Non woven textile fibres can be incorporated into organic polymers in order toproduce armoured plastics. The production of this composite material(glass/resins) requires the major part of textile fibres

Textile sector Woven fibers are set on coils an then distributed as aprimary material for a wide range of industrial applicationssuch as safety clothes, ribbons etc.

Optical sector Glass fibers processed on continuousspinning can be employed as a lightconductor, or picture signal conductor.Their diameter is larger than textilefibers and they are coated with a glasscylinder of lower refraction rate.

Insulation glass (glass wool)it looks like a tangled mass of short fibers of very thindiameter (some microns). Their composition requires moreimportant quantities of alumina, and Anhydrate Bore forfew oxide alkaline compounds than current industrial glass.


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Glass is therefore a complex material due to the variations of

chemical composition and shape brought about by the industry. We

can find this diversity in a certain number of waste made of glass or

containing glass, which implies that their recycling require an

efficient and rational preliminary sorting.

2 Glass recycling channels

As for paper/cardboards and plastics, glass recycling is first orientated

towards the reintegration of transformed material and disposal after use

in the production cycle.Indeed, the energy costs associated to glass produced from virgin

material (silica) are much higher than those associated to the

transformation of glass waste after sorting and shredding (cullet).

The manufacturing recycling channel uses the majority of

recycled glass but it requires that recyclers sort and prepare the

waste so as to optimize the transportation and the transformation.

Alternative channels do not reintegrate recycled glass in the

production circuit but try to re-use the glass material through

various applications such as in the construction industry or in thearts and craft sector.

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We can distinguish 3 main industrial types of demand for the use of used

glass:

The

manufacturing

channels

2.1

The deposit-and-return system

for glass bottles is mainly used for

beers and soda drinks

Sorted container glass in bulk or

shredded. It is mainly generated by

non returnable beverage bottlesand other containers. It can be

collected by color or bulk.

Flat glass such as glass panes are

co l l ec ted separa te l y f rom

windscreen. Mirrors should also be

collected separately but it is rarely

the case.

Note : The market related to the purchase of fibreglass has low

visibility (specially in developing countries). Indeed this product is

essentially manufactured from cullet and not specifically from used

fibres. However fiberglass generated from composite material, such

as those used in the ship building industry starts being seriously

considered in some African countries.

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The manufacturing channels are all based on heavy technology

investments and we can distinguish two activities, often managed by

different operators:

Collection and sorting of glass waste and residual material

Washing and hygienization for hollow glass from the deposit-and-

return schemes and production of cullet

In the priority regions of ReCoMap, the recycling channel through the

DaR system and re-use of some categories of bottles is effective. The

breweries and soda manufacturers have indeed organized the re-launch

of a system which is not new but which was not proving to be efficient in

the 80’s.The present energy crisis can only reinforce this tendency and there is

room for operators who can cover proximity areas and who wish to invest

time and some means but above all, organisation work in this sector.

Optimization of

the deposit-

and-return

(DaR) system

2.1.1

We can note that a returnable bottle of beer is re-used 6 times a year

during 10 years and that its transport when empty remains not only

economically viable but also benefits in terms of GHG in a 250km

radius from the brewery (when compared to the manufacture of a new

bottle and in a collection scheme partly integrated to the distribution

logistic)

However the system has a few limitations:

Two direct factors influence the economic and environmental

viability of the DaR system: the cleanliness of the bottles and the

efficiency of transport.

Two external factors limit their extension, namely the developmentof the sales of new bottles made of cullet (and often as products

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called « glass shape ready for blowing ») or containers made of

other competing material such as aluminium or PET.

To optimize the DaR system, certain experimental projects have been set

up by breweries and soda manufacturers in an attempt to organize

rationally the system, mainly at the collection stage

Organize a primary collection for retailers (including informal

sellers) : indeed retailers do not always have the space to storeempty bottles and the informal sellers who are often hawkers have

even less storage capacity.

During primary collection, bottles must be counted and the lots

collected must be registered in a book with counterfoils. Indeed

the operation is payable and should be accounted in a systematic

way.

The proximity collection must include the rinsing of the bottles

(cleaning of the outside as well as a disinfection of the bottles is

not necessary as it must be carried out just before the filling of thebottles). The collection should also optimize the filling up of the

bottle racks, by classifying the bottles and ensuring that the racks

are full as far as possible.

The primary collector should be able to have a storage place not

far from the distribution route. Hence the distributor will be able,

in one operation, to load a complete lot of sorted empty clean

bottles as well as the statements indicating their origin.

These four operations, which can be paid by the distributor and the

brewery, contribute to the efficiency of the system at 4 levels:Optimization of the distribution of full bottles,

Reduction of sorting operations and accounting at the reception

Reduction of transport nuisances

Reduction of cleaning difficulties

This optimization also contributes to perpetuate the DaR system or even

to extend it to other selling points or products (alcohols, cosmetic,

pharmaceutical containers etc.)

We can also note that the proximity collection can envisage the collectionof caps (if they are not oxidized or soiled) as they can be recycled within

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the ferrous metal channel but it can also ensure the collection of non

returnable bottles which can go for the glass recycling (cullet)

The supply for container glass at national level, when glass-making

exists, or at international level where it does not exist, is growing for

products sorted at source by color.

Indeed, as seen above, the coloration of glass is based on complex

mixture of pigments (metallic oxides) for which each brewery or other

beverage manufacturer knows the secret and which contributes to the

communication strategy.

The removal of pigments during the melting phase of a cullet is a delicate

and costly operation which can be avoided by grouping a batch of virginmaterial together with a homogeneous cullet batch for a given

production batch. It represents therefore the possibility for the distributor

to pay less for a delivery of new bottles and therefore to buy for slightly

more the delivery of sorted returned bottles.

We can note that it is at the voluntary deposit stage at regrouping points

or at civic amenity centers that the sorting of waste by color must be

proposed and this initial sorting can eventually be optimized.

There is still a debate to find out how many colors of glass should be

sorted but a general rule tends to limit to 3 groups the colorimetric sortingfor cullet to be used for the manufacture of colored glass:

The collection of flint glass (clear) is made separately and corresponds to

a regular and constant demand. In fact, this general rule depends also on

the demand of glass-makers and therefore varies with the applications

which lead the market (flat or container glass, fiberglass etc.)

Optimization of

colorimetric

sorting

2.1.2

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Figure 6: The three colorimetric groups

Once a rigorous, colorimetric sorting has been undertaken, the filling up

of the transportation skip can be optimized with a preliminary crushing,

which is carried out preferably with a slow roller shredder which crushes

the bottles and reduces it in fragments of size required by the glass makers

and without generating dust.

Figure 8: Glass shredding

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Ocre

Red et Blue-green

Brown

Purple

Blue

Green

Red et Blue-green



Furthermore, in any case, one must ensure that the demand of the glass

makers specially the price proposed are satisfactory knowing that at this

stage of the negotiations, criteria other than the colorimetric sorting must

be taken into account :

Minimum tonnage to be catered for per period and for each type

of product

Maximum tonnages accepted per periodThese two parameters will allow the definition of storage needs (volume

and duration of storage) which in turn will enable the determination of

needs for the washing of the shredded glass.

We can also recall that the rules for colorimetric sorting can vary from a

glass maker to another and that it is always better to have several clients

rather than one. It is therefore better to adopt quite flexible sorting criteria

in order to favor the sales in continuous flows rather than the sales with

slightly higher profit margins but subject to the risk of a restricted market.

Clear glass

We usually call clear glass container glass which is not colored. For the

majority of them, they are containers of food products but there are also a

large range of special containers of cosmetic and pharmaceutical

products.

Optimization of

the collection

of clear glass

and flat glass

2.1.3

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Figure 9: Typology of clear glass

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No particular precaution except during handling. Beware of spilling residual liquids.

Handle with care. De-metallise (capsules, bases). To be identified regarding their contentwhich can be hazardous even with very small residual quantities.

To be identified regarding their content which can be hazardous even with very small

residual quantities.

Shall be depolluted prior to transportation and treatment such as de-metallisation, shredding.


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Note: Light bulbs and fluorescent tubes do not really form part of

this category but are included in the category of special waste as

they can contain POPs. Only incandescent bulbs which are

gradually being replaced by low energy light bulbs which are

assimilated to special waste can enter this category of clear glass.

In conclusion we note that the collection of clear glass is made byseparating 2 main categories;

Clear glass (non hazardous)

Bottles and other containers which have been used for

food products

De-metallized incandescent light bulbs

Containers used for pharmaceutical products or other

special uses (eg medical laboratories) after identification

of content, harmlessness certification and de-

metallization if necessary.

Hazardous Clear glass (special waste)

Light bulbs and fluorescent tubes if not complete

Containers used for pharmaceutical products or other

special uses (eg medical laboratories) after identification of

content and no certification of harmlessness

Flat glass:

We generally distinguish 3 main categories of flat glass:

Simple or insulated glazing (rare in our targeted countries)

Vehicles windscreens and some special glass (rare in our targeted

countries)

Cathodic tubes

Except for cathodic tubes which require a complex treatment and are thus

special waste, the two first categories are easy to identify and must be

collected separately.

It is also possible to collect the first category (simple glazing) together withclear container glass used for food products.

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Windscreens are subject to a special recycling process and can be

considered as undesirable waste which « pollute » the loads of clear glass

or simple flat glass and disqualify it for sale.

In terms of quantity this category of material is not very representative

(<8%) when compared to container glass. Their collection is therefore

often neglected even if they have a certain value and are relatively easy to

store. In our targeted countries it would be opportune to envisage

grouping actions on a large territory in order to reach minimal quantities

required for negotiation on the recycling market.

Before envisaging an alternative recycling option, one must analyze the

benefits which can be drawn from this strategy.

If it is clear that the manufacturing channels are stable and that they have

capacities to absorb the recyclable glass produced in the priority regions

of ReCoMap, it not less true that the offer is not always attractive.

Indeed, in the priority regions of the programme, the situation is made

difficult due to 3 parameters:

The glass generated does not represent a large volume and is

found in a scattered way when compared to large urban areas.

There is no separate collection or accompanying measures

(information on sorting at source, or sorting at regrouping

centers) which could favor a fine selection of waste

It is sometimes necessary to drive long distances on roads with

limited practicability to bring the sorted waste to treatment centers

or to export zones. Moreover the volumic reduction is not often

carried out.

These 3 parameters increase the cost of operations preceding recycling

itself so much so that the value of the offer for the exportation of a ton of

these wastes (low quality) is probably less than the expenses associated to

the delivery of the material FOB.

2.2 Alternative recycling options

A complementary

strategy with a

local dimension

2.2.1

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Of course this analysis is based on general observations and can be

questioned, in some of the targeted countries, by the setting up of logistic

projects or selective collection, but these favorable situations are rare. It is

therefore legitimate to review possible local alternatives for glass

recycling, as it has been carried out for plastics and paper/cardboards.

We can also note that glass powders are used in numerous extruded

plastics and there is therefore an obvious technical link between this two

recycling channels.

A local recycling alternative must not only avoid the barriers which are

associated to manufacturing options but must also be able to get back

or dedicate part of the material treated to those options. In any case, acomparative analysis is essential to decide which of a manufacturing

or an alternative option, or a mix of both, will be more viable.

Glass as aggregates or powder in concrete

Cement industry has long gone beyond the experimentation stage ofintegrating glassfibre (fibre composite concrete) in special concrete and it

is engaged since recently in the integration in cement of waste and

industrial residuals such as fly ashes, silica smokes and other residual

waste from furnaces. High expectations exist about these new industrial

products for the coming decade.

In this innovation context, it is already possible to use for road works or

individual structures, glass powder as additives or as substitute to cement

and aggregates replacing basalt, flint or traditional granites.

The substitution of part of cement by powders made of used glass indeedimproves the reaction alkali-silica which can be even better controlled

The integration

in concrete andother construction

material

2.2.2.

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thanks to the addition of lithium carbonate but it is considered that the

proportion of glass powder should not exceed 15% of the fraction of

cement in concrete.

Regarding the inclusion of rough fragments of crushed used glass (with a

regular granulometry) in substitution of traditional mineral aggregates, it

is the final material resistance capacity which limits the proportion but for

structures such as ground slabs or facades, substitution up to 30% have

been undertaken. We can note that in most cases it is recommended that

in a view to comply to the requirements of the mixing proportions, the

concrete should have a ratio water/cement of 0,45.

In order to set up this alternative recycling process, we must proceed in 3

main steps as shown below:

Figure 9: Selective sorting of clear glass

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Figure 11: Representation of the production cycle for cement with addition of recycled glass

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The following steps are the usual stages for the preparation of concrete,

namely:

Dry mixing of cement and glass powder

Dry mixing of quarry aggregates, sand and glass pellets

Storage and distribution

Mixing with water and ready-to-use

Cement is necessary to the fabrication of concrete but it is a costly

material which becomes less and less accessible in developing

countries. Moreover it is generally admitted that the production of 1

ton of cement generates 1 ton of CO2 and consequently it is

responsible of approximately 5% of GHG emission on the planet.

Hence the substitution with recycled glass powder and glass

fragments is certainly a promising solution both for the recycling of

glass material at local level and for the continuity and economic

feasibility regarding the improvement of habitat in the targeted

countries of ReCoMap.


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