Quick Dry Refractory Castables to Reduce the Downtime of

Foundry Furnaces

Dirk HOLLAND

CastTech 2012 Krefeld, 8th November 2012

Reduction of Refractory Consumption and the related constraints ….

Monolithic refractory developments during the last two decades have enabled Foundries to greatly reduce their refractory consumption

The associated compromise is often the reduction in plant availability due to longer drying times

Some foundries are even forced to invest in additional equipment which are ready lined and pre-dried to speed up the production start after maintenance work

One area in which this compromise was very clear was the introduction of Low Cement (LC) and Ultra Low Cement (ULC) Castables for Channel Holding and Pressure Pouring Furnaces

Channel Furnace Lining

The lining of Channel Holding Furnaces and - Presspours has to be well planned in advance and any necessary installation work must be undertaken during long non-production schedules like summer or winter break.

Owing to the scale and complexity of these furnaces, these periods must typically have a duration of 17 to 23 days to allow for refractory setting, curing and drying

All this has to be strictly controlled in order to achieve the full benefit of the technology

In the event of unplanned maintenance this can only mean a great loss of production for the foundry

100 t Channel Furnace Lining Concepts

Combined bricks

Dry Vibratable Material ULC Castable

Drying 5 to 6 days Drying 5 to 6 days Drying 8 to 10 days

The Quick Dry - Castable Concept

In 2009 Calderys began to develop a completely new type of cement-free refractories, now known as the QD™-castable range

This new binding system, based on fine mineral components, allows drying times reduction up to 50%, depending on the type of furnace and raw material selection

In addition to the reduced drying time after demoulding, no curing is necessary, so that the burner can be started immediately

Due to the way QD™ evacuates water, it can be considered a safer product in terms of reduced explosion risks compared to cement bonded castables

Quick Dry No Cement Castables

Introduction:

QUICK DRY NO CEMENT CASTABLES• Flexibility and Ease of installation

• No curing time• Drying times heavily reduced

Technology definition:

Quick Dry No Cement Castables

In Situ Steam Pressure Measurements

2mm

specimen30x30x12 cm3

Radiant Heaters5000W - 600°C

Thermocouples

Pressuretransducer

thermalinsulation(ceramicblocks)

Balance

2mm

specimen30x30x12 cm3

Radiant Heaters5000W - 600°C

Thermocouples

Pressuretransducer

thermalinsulation(ceramicblocks)

Balance

Massive bloc (30 x 30 x 12 cm3)

Unidirectional andFast heating (110 °°°°C/min – hot face)

Continuous vapour pressure & Temperature measurement

No difference in corrosion between CALDE™ CAST UT 94 and CALDE™ CAST NT 92 QD

Cup test for Channel Holder

QD

Customer Details

Leading German Automotive Foundry

ABP IRT 115 Channel Holding Furnace with 1,2 MW inductor

Prime melting unit (feed furnace) Küttner unlined Cupola

SG Base Iron (Feed Temperature 1540oC Tap Temperature 1480oC)

Normal Lining CALDE™ CAST UT 94

Normal life – 2-3 yrs (+450k tons iron)

Reason for QD™ – Castable Application

Normal installation including wrecking and drying takes ~ 23 days

Customer demand is for a 17 days maximum

QD™ Option offered and accepted following success in Press Pour Furnace Repair November 2010

Lining Design

BATH - Wall

Insulation Plate: 10 mm ceramic fibre board

Insulation Lining: 100 mm CALDE™ CAST MW STRONG LITE

Safety Lining: 50 mm CALDE™ GUN M 32

Hot Face Lining: 279 mm CALDE™ CAST NT 92 QD™

SPOUTS & COVER LINING

Detachable Spouts fully installed with CALDE™ CAST NT 92 QD™

INDUCTOR

Front Lining: CALDE™ MIX M S 86 BTI

Fitting of Ceramic Felt

Gunning of Back Lining and Surface Finishing

Former Preparation

Pump Casting of CALDE™CAST NT 92 QD™

Former Removal

CALDE™ CAST NT 92 QD™

Burner Assembly

Placement of Thermocouples

and

air ejectors

A good Burner and Supervision are Key for

Success

Installation Details

BATH LINING(Excluding Spouts and Cover)

Insulation Layer ~7.5 t CALDE™ CAST MW STRONG LITE

Safety Layer ~7.5 t CALDE™ GUN M 32

Hot Face Layer 36.8 t CALDE™ CAST NT 92 QD™

QD™ CASTING WATER(Recommended Range = 4.8 to 5.4%)

3200KG @ 5.4%

4800KG @ 5.0%

28800KG @ 4.75%

Total Water Installed = 1780 Litre = 4.84%

QD™ CASTING TIME(2 x 800kg Pump)

6200KG per Hour

Comparison of typical Heating Curves IRT 125

Channel Furnace 160 ton Example

0

200

400

600

800

1000

1200

1400

1600

0 24 48 72 96 120 144 168 192 216 240

time, hrs

Tem

pera

ture

, °C

Cement bonded castables (380mm thickness)

QD NCC (> 380mm thickness)

CALDE™ CAST NT 92 QD™ versus CALDE™ CAST UT 94

5 days saved

CALDE CAST NT 92 QD™

CALDE CAST UT 94

1 Week Production Saved

QD™ INSTALLATION

ULCC INSTALLATION

OBJECTIVE ACHIEVED!!!

QD™ Range for Foundry Ladles

CALDE ™ CAST NB 82 QD™ (for Iron & Steel)Bauxite based

Medium densitiy: 2,82 kg/dm³

high corrosion and abrasion resistance (6,2 cm³ following ASTM)

High Cold Crushing Ctrength

Very good thermal shock resistance

CALDE ™ CAST NA 55 QD™ (for Iron)Andalusite based

low density: 2,51 kg/dm³ >> good thermal insulation

Very good thermal shock resistance

CALDE ™ CAST NM 62 QD™ (for Iron)Mullite based

Low density: 2,55 kg/dm³ >> good thermal insulation

Good corrosion and abrasion resistance

CALDE ™ CAST NT 92 QD™ (for Steel)Tabular Alumina based

High density: 2,96 kg/dm³

Excellent corrosion resistance

High Cold Crushing Strength

Time Saving

The curing - air setting is shorter than LCC, about 50%-75% shorter, 12-24

hours can be saved

Immediate heating after former removal is possible. This means the ladle

can be set into drying much quicker

Drying cycles are about 60% shorter, and up to 48 hours

can be saved compared to Low Cement Castables

Energy savings for Ladles thanks to QD™ Range usage

Hours of initial sintering/heat up LCC QD NCC

2 ton transfer ladle 72 24

1 ton transfer ladle 48 24

2 ton - treatment ladle 54 30

3 ton pouring ladle 72 36

1,5 ton transfer ladle 56 24

• Figures show some example on ladles traditionally lined with LCC and alternatively with QD™ castables and the significant savings in time and energy.

24 – 48 hours saved!

Repair of ladle bottom in cold or warm condition by using the QD™ range

• Possibility to repair bottom in a cold condition or with residualheat in, can be done and gives the advantage to get back intoproduction in very short time, the drying can be minimised andthe repair shows very good result also with respect of thehandling and to stressed heat up/sintering.

Picture shows a repair in a cold ladle. The ladle can be brought in the preheating station after 4-6 hours and be fired at 75-100°°°°C/hour with

very good result.

Advantages of QD™ Castables in Foundry ladles

Flexible in working temperature intervals

Easy to repair

Short curing time and drying cycles

Safe drying cycles

Less demanding preheating

Lower energy consumption during drying

Less sensitive forthermal cycling

QD™

Conclusions

Advantages with the new QD™ - range proven on the field:

Energy savings during dryout / sintering

Shorter cycles = shorter turn around time

Up to 60 % time saving = up to 60 % gas/energy consumtion

Installation advantage

No curing time = shorter turn around time

Easy installation

Favourable thermal shock resistance

Advantages for preheating and cold tapping

Less sensitive to thermal cycling

Leads to prolonged life length

Faster turn around: Refractory installation times can be reduced byseveral days resulting in higher ladle availability and flexibility

Overall improved performances!

Summary

The success of recent furnace projects clearly demonstrates the real benefits of the new QD™ technology, which has been applied in many variants. The number of references is increasing daily in all areas of the foundry: Press Pour Furnaces, Channel Holding Furnaces, Cupola, CIF, Ladles, and Launders etc.

No special equipment or skills are required for the installation and drying of QD™ materials beyond those required for conventional castables. Savings can be achieved in both downtime and fuel consumption