INTERVIEW: PHOENIX AWARD WINNER

COMPANY PROFILE: SGD’S FURNACE NUMBER 2

BATCH PLANT

WWW.GLASS-INTERNATIONAL.COM

I N T E R N A T I O N A L

June 2018—Vol.41 No.6

A GLOBAL REVIEW OF GLASSMAKING

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Whenreliability is not negotiable.

ZIPPE – BECAUSE WE DO IT.

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Batch Plants • Cullet Plants • Factory Cullet Recycling • Automation

Modernization • Engineering • Glass Recycling • Batch Charging

Glass Level Controlling • Preheating • Maintenance & Service

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Premix technology for improved distribution of minor materials

Dr. Sebastian Woltz* of EME discusses premix technology and high-lights its advantages and beneits. The com-pany’s experience in re-cent years has been that dosing and mixing accu-racies of minor materials and their homogeneous distribution in the batch is particularly important to meet increased quali-ty demands.

EME is a member of the Sorg

Group and is active

in the ield of raw material, batch and cullet handling for all sectors of the glass industry.

It provides turnkey plants and single components, process technology, projecting and planning, construction and engineering, project managing, installation and commissioning.

Aside from the major raw materials such as sand, soda ash, dolomite and feldspar, minor ingredients, such as luxing agents (e.g sodium sulphate, luorspar), ining agents (e. g. sulphates, arsenic, antimony, luorides), colourants (e.g selenium, cobalt oxide, iron oxides or salts) or decolourisers (e.g selenium, cobalt) are also part of a batch formulation in the glass industry.

The challenge is to achieve a perfectly blended batch regardless even if there are

� Fig 1. EME automatic premix technology.

Continued>>

raw materials with extremely different ratios included in the batch formula.

It must be guaranteed that the minor

additives are also well distributed in the batch. The risk of raw materials cross-contaminating different furnaces when producing glass of different colours in a single batch plant must also be considered in the concept. Physical and chemical

homogeneity of the batch is of upmost importance to achieve stable conditions in the melting furnace and yield glass products with maximum strength and aesthetic appearance. Therefore the batch mixing technology must be designed to meet high demands.

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Distribution considerations Typical batch compositions for the production of different colours in the container glass industry are listed in Table 1 to show the differences in batch formulas.

There are huge differences in the ratios

of the batch components (e.g sand 64.3 % in comparison to selenium 0.0009 %). For minor materials, much stricter requirements are demanded of the

equipment with regard to dosage and weighing ranges as well as accuracies (e.g weighing capacity may vary from 3.500kg for sand down to 200g for colouring agents). When dosing and weighing them directly in the mixer, sensitive dosing and scaling laboratory-type equipment must be installed.

The implementation under normal batch house conditions, with limited

space, is dificult and challenging. Another important issue to consider is

that the entire minor material must be distributed in the batch without any losses during transfer and mixing.

In addition the wetting of the batch in the mixer, through the surface wetting of all particles, creates a tacky state of the batch and makes it more dificult to distribute the minor materials evenly.

Considering these aspects, it is common to premix the minor raw materials rather than to dose them directly to the mixer.

The premix technology In general, premix means a mixture of minor materials with a major component of the batch as carrier material (Fig 1).

To achieve a uniform and homogenous

premix, the carrier material should have similar nominal grain size, similar grain

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Modified: Date: Name: Date:

File:

Draw no:

Offer no.:

Draw. by:

Name: Wockerather Weg 45

D-41812 ErkelenzTel:+49 2431-96180Fax:+49 2431-74687

© by EME GmbH [Form A2 420x594

Liste der allgemeinen AbkürzungenABBREVIATIONS USED IN THIS FLOWSHEETAbréviations utilisées dans ce schema functionnel

AC = Automatische Waagenkontrolle AUTO CHECK FOR SCALE contrôle automatique des balances CC = Stromkontrolle CURRENT CHECK contrôle du courantEMV = Elektromagnetventil ELECTROMAGNETIC VALVE électro magnetic vanneEBRA = Elektronische Bremse BRAKE THYRISTOR CONTROLLED frein électroniqueELS = Notendschalter EMERGENCY LIMIT SWITCH interrupteur de fin de course d' urgenceFIC = Filterreinigung FILTERCLEANING nettoyage du filtreFMIN = Füllstandmessung leer FILLING LEVEL INDICATOR MIN indicateur de niveau min.FMAX = Füllstandmessung voll FILLING LEVEL INDICATOR MAX indicateur de niveau max.FMEAS = Füllstandmessung Höhenerfassung FILLING LEVEL MEASURING SYSTEM systéme de mesure de niveauMD = Belegtmeldung MATERIAL DETECTION détection de matérielMM = Feuchtemessung MOISTURE MEASURING mesure d'humiditéIRD = Infrarotdetektor INFRARED DETECTOR détecteur à infrarougeLS = Endschalter LIMIT SWITCH commutateur de fin de coursePTC = Thermistor Motorschutz TEMPERATURE PROTECTION protection du moteur à thermistancePS = Druckschalter PRESSURE SWITCH interrupteur à poussoirePIS = Steckverbindung PLUG IN SOCKET connecteur male-femelleRC = Drehzahlkontrolle ROTARY CHECK relais tachymétriqueRC_BI = Drehzahl- und Richtungskontrolle ROTARY/DIRECTION CHECK relais tachymétrique avec interupteur de secourRPS = Reparaturschalter REPAIR SWITCH interrupteur de réparationRSW = Seilnotschalter ROPE SWITCH corde de délenchement avec interrupteur de secourSAL = Elektronischer Sanftanlauf ELECTRONIC SOFT STARTER démarreur lent électronique SSW = Sicherheitsschalter SAFETY SWITCH interupteur de sécurité SK = Schichthöhenkontrolle CHECK OF LAYER THICKNESS Contrrole de l'épaissuer de la coucheTC = Temperatur Regelung TEMPERATURE CONTROL contrôle de températureTRC = Schieflaufkontrolle TRACK CHECK contrôle de biaisement

Bilder in diesem Fliesschema sind Beispielebereits gelieferter Anlagen und dienen nurder Veranschaulichung.

The pictures in this flow-sheet are examplesof already delivered plants and are to beunderstood as illustration only

Die in den Waagen angegebenen ± xx Werte geben die statische Wägegenauigkeit an. Es sind keine Angaben über die erreichbare Dosiergenauigkeit.The ± xx values mentioned in the scales represent the statical weighing accuracy. They do not stand for the obtainable dosing accuracy.Les valeurs ± xx indiquées dans les bascules réprésentent la précision de pesage statique. Il ne s'agit pas de données de précision de dosage qu'on peut atteindre.

Anlagenteile innerhalb der gelben Flächen sind als Option im angebot enthalten.The plant partswithin the yellow fields are included in our quotation as an option.

AC

AC

AC

FIC

FM

IN

Silo 02 Silo 03

FM

IN

Silo 01 FM

INSilo 04

EMV 5/21xLS

EMV 5/21xLS

FM

IN

EMV 5/21xLS

Premix Hopper 01

EMV /25

EMV /252xLS

EMV /252xLS

Scale 03kg ±xxg40

FM

AX

FM

IN

Scale 01kg ± 5g25

EMV 5/22xLS

FIC

EMV 5/21xLS

EMV 5/21xLS

Scale 02Mixer premix

250 l

FIC

LS

size distribution and similar speciic gravity, should not be hygroscopic and contain no water. In the glass industry, soda ash and limestone are most commonly used as carrier materials; sometimes sand is also used.

The batch is normally wet with water in the mixer to reduce dusting in the melting furnace, save energy and to avoid decomposition and segregation during

the batch transport and storage. However, exothermic reactions of the

water with some of the raw materials (e.g formation of soda hydrates) create a hot and humid atmosphere in the batch

mixer. This results in condensation within the

mixer and the transfer devices (e.g chutes or down pipes). Here the minor additives

clear lint lint dead leaf green

sand 64.3% 61.3% 65.1% 64.8%

soda ash 18.7% 21.7% 18.5% 18.4%

limestone 16.6% 16.8% 16.2% 16.2%

selenium 0.0009% - - -

salt cake 0.38% 0.22% 0.07% 0.17%

iron chromite - - 0.01% 0.09%

iron scale - - 0.03% 0.19%

carbon 0.014% 0.01% 0.06% 0.15%

� Table 1. Typical batch composition of container glass.

� Fig 2. Principle low sheet automated

premix preparation.

� Fig 3. Barrel tilting station for minor materials.

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would tend to stick, if they were not embedded in a carrier material.

Also the risk of sticking to a mixer paddle or on the inside surface of the mixer will be reduced signiicantly, when the minor raw materials are not introduced directly to the mixer but rather distributed via a premix.

Another advantage is that the premix storage, dosage and mixing equipment can be located away from the main mixer and therefore the transfer devices of the minor material to the pre-mixer can be designed to be as short as possible to minimise transfer routes and transport losses.

The more sensitive dosing and weighing equipment can also be better protected against environmental conditions such as vibrations, dust or iniltration.

The iltration system of the pre-mixer can be optimised according to the special conditions, for example avoiding sucking of the minor particles into the ilter. Due to the possibility to produce larger premix batches, the dosage and scaling equipment can be engineered with greater weighing ranges and more industrial equipment can be installed (Fig 2).

Despite the fact that the risk of losses of the minor raw materials is lower with the premix technology, the possibility to have a more

homogenous distribution of the minor materials in the batch exists. The risk of cross-contamination of different furnaces when producing glass of different colours in a single batch plant will also be reduced.

Cross-contamination remains a major concern since only traces of amounts can have an impact on the furnace performance and the inal product quality (Fig 3).

Provisions to avoid the transporting of lint and coloured batches on the same conveyor belts highlight this issue.

The premix can be executed manually (manual - by hand - weighing and feeding of the premix raw materials to the premix mixer and manual feeding to an intermediate storage bin), semi-automatic (manual weighing but automatic transport to an intermediate storage bin) or full automatic (automatic feeding, dosing, weighing and mixing).

In smaller production plants, it makes sense to execute the premix manually or semi-automatically since the volume of additives is small and the applied scaling and weighing technique is sensitive and costly (in proportion to the related investment required for the complete batch plant).

Special attention must still be paid to de-dusting requirements associated with toxic materials, such as selenium and cobalt, to meet the local safety regulated limits which are often critical with manual handling.

The main disadvantage of the premix technology is the additional investment that has to be made.

Nevertheless, if a premixing unit is not foreseen during the irst stage, it is important that the layout and the concept of a new batch house are always designed in such a way that a future upgrade can be executed without any major structural changes. �

*Area Sales Manager, EME, Erkelenz, Germany. www.eme.de

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