No.17 | December 2015

Dear Friends,

Wish you and your dear ones a Very Happy & Prosperous New Year 2016!!

Like everyone, I too believe that the New Year would bring back smiles on our faces, thanks to the reports on better times and recovery of lost momentum in economic growth. The year that has just gone by would be one that many of us probably would like to forget in terms of business evolution. The China effect, market and currency fluctuations, spiraling down oil prices, terrorism and general global growth stagnancy have stamped an awful impression in the business space. Nevertheless,

for many of us, this situation offered an opportunity to innovate and explore robust strategies and solutions.

The 2nd National Seminar on Advances in Refractory Raw Materials and Monolithics was jointly organized by Kerneos and CSIR-CGCRI on 19th November 2015 in Kolkata. The seminar was inaugurated by Dr. J.N. Tiwari, ED of OCL India Ltd. and Chairman of IRMA. Director of CSIR-CGCRI, Dr. K. Muraleedharan welcomed the guests and participants. Dr. Christoph Wohrmeyer, Senior Technical Director -Kerneos delivered the key note address.

Experts in the field presented thought-provoking and relevant technical papers on various topics including beneficiation or value addition to the natural raw materials, synthetic refractory raw materials, refractory castables and binder systems. These presentations ignited a debate on optimizing available natural resources and working on new areas of opportunities. Depleting resources is a concern and with increasing emphasis on environment protection, necessity for alternate and cost effective raw materials and resources was in focus.

Kerneos is a Platinum Sponsor of IREFCON16 being organized by IRMA to be held in Hyderabad from 20th to 22nd January 2016. We are actively participating in this event through two lectures and an exhibition booth.

This special issue of Secar Gazette covers among other regular columns, a technical article on Rapid and reliable repair of refractory lining with dry gunning.

Segi P. Idicula, Managing Director Kerneos India & Middle East Operations

Although dry gunning is well known in India, its potential to replace traditional methods of patch repair is yet to be realised to a large extent. This is possible with relatively small investment in equipment and skilled personnel together with appropriate mix design. The article on page 3 discusses the levers of mix design to achieve desirable gunning performance.

(Full Paper on Page 3)

Glimpses of the Seminar on Advances in Refractory Raw Materials and Monolithics held in Kolkata on 19th November, 2015

We have moved to our new office:

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4A, Camac Street, Kolkata 700017

Tel: +91 33 4452 2300

Fax: +91 33 4452 2333

Tech Edge

India is the second largest producer of cement in the world. India’s cement industry is a vital part of its economy & infrastructure growth. It provides employment to more than a million people, directly or indirectly. This sector was de-regulated in 1982, the Indian cement industry has attracted huge investments, both from Indian as well as foreign investors.

The country’s per capita consumption is around 190 kg, which is lower than the World average which is around 500 Kg, providing further room for demand in the industry.

India’s potential for development in the infrastructure and construction sector will largely benefit the cement sector. Some of the recent major government initiatives such as development of 98 smart cities are expected to provide a major boost to the sector. Expecting such developments in the country and aided by suitable government foreign policies, several foreign players such as Lafarge-Holcim, Heidelberg Cement, and Vicat have invested in the country in the recent past. Present situation is as stated below:

• LargeCementPlant:188

• Mini&WhiteCementPlants:365

• Domestic cement consumption isexpectedtohavereached324milliontonnes in FY15 from 165.63 milliontonnes in FY11

• Theconsumption is furtherexpectedto increase at a CAGR of 15.7 per cent during FY11-17 and reach 398million tonnes

• Demand will be supported byinfrastructure development in tier 2 andtier3cities.

Ready availability of the raw materials like limestone & coal aids the growth of this sector. India’s cement demand is expectedtoreach550-600milliontonnesperannum(MTPA)by2025.Thehousingsector is the biggest demand driver of cement, accounting approximately 67% of the total consumption in India.The other major consumers of cement includeinfrastructureat13%,commercialconstruction at 11% and industrial

Domestic cement consumption in inDia & future trenD

constructionat9%.

Government Initiatives : In the 12th Five Year Plan, the Government of India plans to increase investment in infrastructure to the tune of US$ 1 trillion. The Cement Corporation of India (CCI) wasincorporated by the Government of India in 1965 to achieve self-sufficiencyin cement production in the country. Currently, CCI has 10 units spread over eight states in India. In order to help the private sector companies thrive in the industry, the government has been approving their investment schemes.

India has joined hands with Switzerland to reduce energy consumption and develop newer methods in the country for more efficient cement production, which will help India meet its rising demand for cement in the infrastructure sector. The Government of India has decided to adopt cement instead of bitumen for the construction of all new road projects on the grounds that cement is more durable and cheaper to maintain than bitumen in the long run.

Road ahead, the eastern states of India are likely to be the newer and virgin markets for cement companies and could contribute to their bottom line in future.

In the next 10 years, India could become the main exporter of clinker and gray cement to the Middle East, Africa, andother developing nations of the world. Cement plants near the ports, for instance the plants in Gujarat and Visakhapatnam, will have an added advantage for exports and will logistically be well armed to face stiff competition from cement plants in the interior of the country. Other foreign players are also expected to enter the cement sector, owing to the profit margins and steady demand. With help from the government in terms of friendlier laws, lower taxation, and increased infrastructure spending, the sector will grow and take India’s economy forward along with it.

(Source: Cement Manufacturers’ Association

(CMA), Planning Commission, TechSci research)

Market Pulsetechnical news:

CSIR-Central Glass and Ceramic Research Institute, Kolkata and Kerneos India have completed a joint study on “Development of High Alumina Aggregates from Sillimanite Beach Sand and its Application in Refractory Castables”. High density mullite aggregate with porosity <1% was successfully produced from sillimanite sand with industrial techniques, such as roll briquetting and nodulization and their performance in refractory castables was evaluated.

Dr. Goutam Bhattacharya will present the following paper during IREFCON 2016 in Hyderabad.

synthetic mullite aggregate from sillimanite beach sand for improved castable linings

G. Bhattacharya1, C. Wöhrmeyer1, C. Parr1 1Kerneos, Kolkata, India

H. S. Tripathi2, A. Ghosh2 2CSIR-Central Glass & Ceramic Research Institute, Kolkata, India

Safety Wall

technologies and innovations

Kerneos active in the world of Science

Kerneos is fully integrated in the scientific community, both as a player in research and as a sponsor of major international congresses.

After a century of research and development, Kerneos offers the scientific community an unequalled fund of knowledge and experience in calcium aluminates. Kerneos research teams have formed productive partnerships with internationally recognised universities. These projects ensure that the company retains the highest level of expertise in calcium aluminate technolology.

Kerneos supports 18 projects doctoral or post-doctoral research projects with universities and research centres worldwide:

• 3intheUnitedStates

• 5inFrance

• 3inSwitzerland

• 4inGermany

• 3inChina

Kerneos Corner

safety is at the heart of Kerneos’s corporate culture

Safety and quality are the pillars of our corporate culture and form an integral part of the Group’s Sustainable Development approach. For many years now, Kerneos has been committed to

continuous improvement programmes with respect to performance in these areas, through a management system that is ISO 9001 and OSHAS 18001 certified.

With the launch of prosafe the goal is to ensure that kerneos meets the most demanding global standards, with the aim of achieving 0 accidents for all employees and subcontractors.

RapidandReliableRepaiRoFReFRaCtoRylininGwithdRyGUnninG

introduction:

Monolithic refractories have, not only evolved in composition from conventional castables to deflocculated castables, but also incorporated new installation techniques including dry and wet gunning. In India, a traditional method of repair or patching is slow, unsuitable for deflocculated low-porosity castables and depends on the skills of masons, who are often untrained for refractory applications and end up adding more water. The cost of poor performance or failure can be high in a highly competitive scenario. Often downtime costs many times more than the material and installation cost. Moreover, labor cost has increased considerably and is reaching a point where faster and reliable equipment based installations [1] are gradually replacing labor intensive manual installation.

Dry gunning is well known to many manufacturers. However, there is enough opportunity of further penetration of this technique replacing traditional methods of repair. It has the advantage of finishing the lining or repair rapidly compared to the traditional methods, although it creates dust in the installation area and can have high rebound loss. The more recent developments have focussed on wet gunning or shotcreting application, which overcomes the main disadvantages of dry gunning i.e. dust generation and rebound loss. Despite dust generation and relatively high rebound loss compared to wet shotcreting, dry gunning involves simple arrangement and inexpensive equipment. also, it requires only 2-3 skilled gunners tocomplete the installation. Wet shotcreting is relatively complex and requires around 5 skilledpersons and often preferred for relatively large installations(>50t).theinstalledpropertiesofdrygunning are generally not as good as vibration casting or shotcreting. Dry gunning compositions are often conventional - high cement based. This study will concentrate on traditional high cement based dry gunning compositions, which dominate significantly in India.

This article investigates the dry gunning compositions and discusses the formulation levers, which can be used to reduce the rebound loss and dust generation.

materials:

Model gunning compositions (table1) basedonchamotte aggregate were designed to evaluate the effect of different calcium aluminate cements and a selection of additives, which includes a rheologicalmodifier(plasticclay),lithiumcarbonatebased accelerator and a reactive calcium aluminate cement (CaC) based mineral phase. Secar® 71 and Secar® 80 were used in combination with

G. Bhattacharya*, C. Wöhrmeyer and C. Parr, *Kerneos, Kolkata, India

other materials as shown in the Table 1. Secar®

71 is a versatile pure cement used for all types of

monolithic installations. Secar®80 is a high purity

engineered cement with optimised flow and water

demand in casting application. A small addition

of plastic clay to the base composition provides

sufficient plasticity. Dinger and Funk model was

used to optimise particle size distribution to obtain

a distribution modulus of 0.2, which previous

experiments showed to be optimum for gunning

performance. Figure 1 shows actual particle size

distribution against the target.

experimental details:

analivarotorgun(Figure2)wasusedwithadry

material feed without pre-damping. Water was

suppliedusingahighpressurepump(8bar)from

a storage tank coupled with a scale to measure

quantity of water addition. The gunning nozzle was with 1000mm extension from water mixer to thenozzlebody,whichwas300mmlongwithatapered outlet of 35mm. Gunning pressure wasmonitored with a pressure gauge and kept from 2-2.5 bar. the gunning hose was 20m long.250kgdrymaterialwasgunnedforeachtestona vertically suspended marine plywood board. 150mm nails were placed inside the board tosupport the gunned mass. The gunning rate was 2-3t/h.

Water was adjusted for each test to have minimal rebound. The rebound after each run was weighed and calculated after considering correction for water content in the gunned mass and non-adhered mass. A thermocouple was inserted into the gunned mass and the exothermic profile was recorded. The development of hardness with time was followed using a penetration needle (Maynadier),whichgaveresistancetopenetration(kg).hardenedsampleswerecoredafter24handmechanical properties were tested after drying and firing at different temperatures. The samples were inspected for any defects such as laminations before testing. It was found to be defect free in general.

results:

Gunning properties: All compositions generated very little dust. However, significant differences were observed in terms of water addition and rebound loss among the compositions. Rebound loss, majority of which was generated during the early stages of adjustment was generally high for each composition, probably because relatively small quantity of material was sprayed on the plywood panel. The rebound could have been significantly less, if larger quantity of material had been gunned.

thebasecomposition(a)with2%plasticclaydidFigure 1: Particle size distribution of model gunning composition

Figure 2: Schematic of dry gunning

table 1: model gunning compositionsRaw Material Size/

mmA B C D E

Chamotte : 40/42% Al2O3 3-5 12 12 12 12 12

Chamotte : 40/42% Al2O3 1-3 24 24 24 24 24

Chamotte : 40/42% Al2O3 0-1 32 32 32 32 32

Chamotte : 40/42% Al2O3 0-0.1 10 10 10 10 10

Plastic Clay 2 2 2 2 2

Secar cement 20 20 20 20 20

Total 100 100 100 100 100

Plastic clay +3

Li2CO3 based accelerator +0.2

Reactive CAC based additive

+0.5 +1

0.1

1

10

100

1 10 100 1000 10000

% p

assi

ng

microns

CalculatedTarget

q = 0,2

Air inlet Gunned mass

Marine board

Pressure gauge

Water Scale Material Pump

35 mm300 mm1000 mm

Data logger f(t°c)

Kolkata Office: KERNEOS INDIA# 4B-PS Arcadia Central, 4th Floor , 4A, Camac Street, Kolkata 700017, India Tel: +91 33 4452 2300 Fax: +91 33 4452 2333

Head Office: KERNEOS S.AImmeuble Pacific, 11, cours Valmy, Paris - La Défense 92800 Puteaux, France Tel: +33 1 46 37 90 00 Fax: +33 1 46 37 92 00

references[1] Parr C., Revais C. and Bier T., Calcium Aluminate Cements for Refractory Gunning Application, The Third International Symposium on Refractories, Beijing, China; 1998.[2] Landman et al, The Rehabilitation of Gunning Refractories, 2nd International Conference on Refractories, Japan; 1987[3]armelinetal,Reboundindry-mixShotcrete,Concreteinternational,Sep1997,p54-60[4]armelinetal,theMechanicsofaggregateReboundinShotcrete,MaterialsandStructures,Vol.31,Mar1998,p91-98

THE

PLUS

FACT

OR

not adhere to the panel and the gunned mass fell for both Secar® 71 and Secar® 80. Hence the resultsofthiscomposition(a)werenotincluded.

Figure 3 shows thewater addition and reboundloss for each composition. Except for composition B, Secar®80 based compositions showed lower wateraddition (12-14%) than thosewithSecar® 71. The rebound loss varies widely as a function of cement type and additives. Secar® 71 based compositionwithplastic clayaddition (b) yieldedthe lowest rebound losses (15.5%). otherSecar®71 based compositions (C and d) alsoshowed low rebound loss (<16 to 17%). Secar® 80 based compositions showed better results with reactive CAC based additive. However, these (<20%)werehigherthanthelowvaluesobtainedwith Secar®71(around15%).lithiumcarbonatebased accelerator developed intermediate results.

Gunned properties: The penetration measurement could not be carried out for highly accelerated C compositions and also for composition B with Secar®80. Composition D with Secar®80 developed similar penetration resistance with time to that of Secar®71. Selective results of penetration resistance of Secar®71 based compositions are shown in Figure 4. no apparent correlation was foundbetween the rebound loss and the penetration

resistance. exo-profile data (table 2) shows veryrapid exothermic reaction for composition C with Lithium carbonate based accelerator. Secar®80 takes lesser time to start heat generation.

mechanical properties: The cold crushing strengths of the compositions show classical changes in strength with drying and firing up to 1100°C (Figure 5). the strengthsdrop from110°C to800°Cdueto dehydration or destruction of hydraulic bond. However, the reduction of strength from 110°C to 800°C is relatively less for Secar®80 based compositions. The loss of strength from 800°C to 1100°C is relatively less.

Discussion:

The performance of a gunned lining depends to a large extent on the gunning quality, which is influenced primarily by the gunning technique and material design. However, it may be difficult to isolate the individual factors of gunning technique and material design to the installed performance. It may also be noted that optimisation of installation parameters such as rebound loss may lead to lower mechanical strength.

A gunning model [2] considers that the gunned mass evolves from a relatively fluid to more viscous plastic state as the gunned layers become thicker. The balance of these layers determines the rebound and adhesion. If the gunned mass stiffens rather slowly, it may cause slumping as it happened with composition A, whereas if it stiffens too rapidly, yield stress goes up leading to higher rebound loss. The rheology evolution is linked to material design and the total water added.

The studies on rebound in the civil engineering sector[3,4]identifythequantityofwateraddition,gunning technique such as nozzle design and

distance from the panel along with material design

to be the key factors. The rheology modifying

additives and particle size distribution are the vital

components of material design as they influence the

yield stress. The models propose that the impacting

particles of the gunning material possess energy of

rebound which needs to be compensated by the

adhesion of particles to the gunned surface. This

energy is affected by water addition and cement

content.

Exothermic profiles do not give any correlation with

gunning performance. The rapid setting materials

did not give the best or the worst performance.

The interactions between each cement type and

the additive are not uniform and therefore, the

optimised composition may need to be developed

for each cement type. Secar®71 may be considered

to be the easiest to work in gunning compositions

as it can give good gunning performance with low

rebound along with excellent mechanical strengths.

conclusion:

Dry gunning is a rapid and reliable method of repair

and can be of significant value for Indian customers

in terms of increase in efficiency of installation and

often quality compared to traditional method of

repair (patching). the dry gunning study reveals

that the combination of cement and additive

type and water addition determines the gunning

performance as measured by rebound loss and

adhesion characteristics. Conventional gunning

compositions, particularly with Secar®71 can be

perfected to have low rebound loss with excellent

installed properties.

table 2: eDX analyses of ccac (figure 4)Max.

temperature (°C)

Start of heat generation (min)

Exo peak time(min)

Secar 71 B 44.5 140 240Secar 80 B 26 17 168Secar 71 C 46.1 <10 75Secar 80 C 31.4 5 120Secar 71 D 47.6 150 270Secar 80 D 28.5 17 175Secar 71 E 45.4 150 270Secar 80 E 27 25 185

0

5

10

15

20

25

30

35

0

5

10

15

20

25

B C D E

Rebo

und

%

Tota

l wat

er d

eman

d %

Total water demand % Secar 71 Total water demand % Secar 80

Rebound % Secar 71 Rebound % Secar 80

Figure 3: Water demand % and rebound % of gunning compositions with Secar®71 and Secar®80

Figure 4: Penetration resistance of Secar®71 based gunned samples

Figure 5: CCS (MPa) of gunning compositions with Secar®71 and Secar®80

0

5

10

15

20

25

0 20 40 60 80 100 140

kg

Time (min)

B (Rebound 15.3%) C (Rebound 16.2%)

0

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60

B C D E B C D E

Secar raceS17 80

CCS

(MPa

)

25h 110°C 800°C 1100°C